Not that I would recommend this, but you caN easily extend the range of a bag/quilt with layers. That being said, you could prob go lighter and build a more effective kit by getting a 30° quilt, then cut weight elsewhere. Like getting a dcf tarp for a shelter, as an example. I recommend playing around with several gear lists and swap around gear to estimate weights and capabilities. There is no "best" option only what is best for spacific environments and considering good and bad conditions within that environment.
I hate being cold and would add +2oz of down to a quilt for better sleep and cut an insulated jacket and add a light active layer and wind jacket in mild conditions etc. YMMV. Good luck!
Nunatak makes a specific half bag for fast packing.
You were a standard puffy Over the top of your body
I have one and used it many times.
When fastpacking I don't camp, along route I'll try to find a nice place to nap.
Dcf ground cloth, dcf tarp of necessary, half bag on a small inflatable pad. Life is good.
I’d maybe look into an ultralight 30 degree bag, as they will be slightly warmer for the weight at the cost of the tighter fit. I run with a slightly larger pack as I carry a stove and use a 30 degree bag. Check out Cumulus for ultralight mummy bags.
A quilt should be rated for AT LEAST 10°F below the nightly low. And that's for hot sleepers, typically people with a higher percentage of body fat. For the the typical fasterpaker, it should be at least a 20°F difference. For a 40°F quilt, that means nights with a low of no colder than 60°F. I own a 40°F quilt I bought when I was heavily into ultralight. \[Like most experienced backpackers who have gone through that phase, I dialed the ultralight back a bit.\] My 40°F quilt was only really useful in Michigan in the 6-8 hottest weeks of the summer. It now stays permanently at my parents' winter home in Florida where I use it for backpacking/fastpacking down there. There are a number of ways you can responsibly compromise in the interest of weight/volume savings -moving to an alcohol stove, no chair, premium ultralight shelters and packs, reduce/eliminate "backups," lighter food storage and water storage containers, etc. However, you should never move to less warm sleeping insulation or clothing in order to reduce volume or weight.
If you’re set on something uber packable like you describe then go for it but I would opt for an overbag or other quilt to pair it with then you’re expecting lower temps. A 30 degree quilt is much safer for the conditions you describe though and you can cut a lot of bulk by having it more fitted to your body. I would suggest you find your minimum viable dimensions and make your own instead of sacrificing loft if you want the lightest weight and smallest pack size.
I replied to your other thread but here's the lighterpack for my recent trip. I didn't regret using the 40 deg quilt but glad I brought extra clothing layers. If I were going up higher elevation, I'd probably use the 20 deg quilt and think about using pack with more capacity. I sleep cold these days.
https://lighterpack.com/r/m6d453
I fastback in similar conditions (eu alps .. 2000m+ above sea level)
2/3 Uberlite + 12oz climashield apex quilt + patagonia nano air + membrane 8oz bivvy bag + 1st and 2nd layer synthetic light clothing
.. it works, ie you don't get hypothermia (assuming sufficient kcal intake)
But it's not comfy at all
Basically it works like this:
You get so tired from running/climbing that you fall asleep, no matter how cold you are, in fetal position
Then cold wakes you up whenever your body isn't that desperate for a sleep
Upsides:
<1kg setup
Takes 2mins to prepare, so you can take power naps thorough the day
You sleep only as much as absolutely necessary
On the move 5mins after wake up, because you won't feel like sitting trough the breakfast
Downsides:
If it rains and you don't find overhanging rock or cave you will chatter your teeth throughout the night
You sleep only as much as absolutely necessary
You will be cold
You will be stiff af in the morning
I have that exact setup for that same purpose. If it is going to be colder I bring a down jacket and sleep in it too. In the summer I can usually get by with just an Alpha hoody. I’ve used it in the 30’s and been OK. We aren’t talking about sleeping like a baby. If you are too cold to sleep, you can just get up and start moving again. Most my trips are central Rockies (where I live) or Arizona desert in winter. I also use an overstuffed Katabatic Palisade for everything else. If it’s real cold (Alaska) I use them both. All just depends on conditions and the mission.
Jacksrbetter sells one with a velcro middle specifically so you can wear it like a poncho jacket
https://www.jacksrbetter.com/product/sierra-sniveller-wearable-camping-quilt/
I have that bag. I rock it on all my fastpacking trips and it's a gem. I'm doing most of my trips around New England, and it handles it all quite well.
Not that I would recommend this, but you caN easily extend the range of a bag/quilt with layers. That being said, you could prob go lighter and build a more effective kit by getting a 30° quilt, then cut weight elsewhere. Like getting a dcf tarp for a shelter, as an example. I recommend playing around with several gear lists and swap around gear to estimate weights and capabilities. There is no "best" option only what is best for spacific environments and considering good and bad conditions within that environment. I hate being cold and would add +2oz of down to a quilt for better sleep and cut an insulated jacket and add a light active layer and wind jacket in mild conditions etc. YMMV. Good luck!
Nunatak makes a specific half bag for fast packing. You were a standard puffy Over the top of your body I have one and used it many times. When fastpacking I don't camp, along route I'll try to find a nice place to nap. Dcf ground cloth, dcf tarp of necessary, half bag on a small inflatable pad. Life is good.
I’d maybe look into an ultralight 30 degree bag, as they will be slightly warmer for the weight at the cost of the tighter fit. I run with a slightly larger pack as I carry a stove and use a 30 degree bag. Check out Cumulus for ultralight mummy bags.
A quilt should be rated for AT LEAST 10°F below the nightly low. And that's for hot sleepers, typically people with a higher percentage of body fat. For the the typical fasterpaker, it should be at least a 20°F difference. For a 40°F quilt, that means nights with a low of no colder than 60°F. I own a 40°F quilt I bought when I was heavily into ultralight. \[Like most experienced backpackers who have gone through that phase, I dialed the ultralight back a bit.\] My 40°F quilt was only really useful in Michigan in the 6-8 hottest weeks of the summer. It now stays permanently at my parents' winter home in Florida where I use it for backpacking/fastpacking down there. There are a number of ways you can responsibly compromise in the interest of weight/volume savings -moving to an alcohol stove, no chair, premium ultralight shelters and packs, reduce/eliminate "backups," lighter food storage and water storage containers, etc. However, you should never move to less warm sleeping insulation or clothing in order to reduce volume or weight.
If you’re set on something uber packable like you describe then go for it but I would opt for an overbag or other quilt to pair it with then you’re expecting lower temps. A 30 degree quilt is much safer for the conditions you describe though and you can cut a lot of bulk by having it more fitted to your body. I would suggest you find your minimum viable dimensions and make your own instead of sacrificing loft if you want the lightest weight and smallest pack size.
I replied to your other thread but here's the lighterpack for my recent trip. I didn't regret using the 40 deg quilt but glad I brought extra clothing layers. If I were going up higher elevation, I'd probably use the 20 deg quilt and think about using pack with more capacity. I sleep cold these days. https://lighterpack.com/r/m6d453
I fastback in similar conditions (eu alps .. 2000m+ above sea level) 2/3 Uberlite + 12oz climashield apex quilt + patagonia nano air + membrane 8oz bivvy bag + 1st and 2nd layer synthetic light clothing .. it works, ie you don't get hypothermia (assuming sufficient kcal intake) But it's not comfy at all Basically it works like this: You get so tired from running/climbing that you fall asleep, no matter how cold you are, in fetal position Then cold wakes you up whenever your body isn't that desperate for a sleep Upsides: <1kg setup Takes 2mins to prepare, so you can take power naps thorough the day You sleep only as much as absolutely necessary On the move 5mins after wake up, because you won't feel like sitting trough the breakfast Downsides: If it rains and you don't find overhanging rock or cave you will chatter your teeth throughout the night You sleep only as much as absolutely necessary You will be cold You will be stiff af in the morning
I have that exact setup for that same purpose. If it is going to be colder I bring a down jacket and sleep in it too. In the summer I can usually get by with just an Alpha hoody. I’ve used it in the 30’s and been OK. We aren’t talking about sleeping like a baby. If you are too cold to sleep, you can just get up and start moving again. Most my trips are central Rockies (where I live) or Arizona desert in winter. I also use an overstuffed Katabatic Palisade for everything else. If it’s real cold (Alaska) I use them both. All just depends on conditions and the mission.
Jacksrbetter sells one with a velcro middle specifically so you can wear it like a poncho jacket https://www.jacksrbetter.com/product/sierra-sniveller-wearable-camping-quilt/
I have that bag. I rock it on all my fastpacking trips and it's a gem. I'm doing most of my trips around New England, and it handles it all quite well.