I just question how long the screws would last on rocks. I'm sure, with enough power, it would be fine on hard pack, grass, and dirt. Water, snow, mud, probably would be best. As long as the screws are big enough to float the engine and frame.

 

Just make the lips on the screw or another hard material and they would hold up against rocks. Heck tere would probobly be a softer material that would just collapse under hard pressure. Tire Rubbber??????