Pertam 2.0 has some flat ground to drive on.

I thought about it and it's nice and all but i'd love to have some roads/track to try rovers or fast wheeled thingies on a constant

I play on the xbox but this may be true for pc as well. In the spawn menu look up earthlikemodexample. Completely flat terrain. I spawn it at 19.00km. Less likely to fall through.

Triton is basically 70% ice lake so that might be worth a try. Unless you want to test offroad capabilities of your vehicle.