Regular truck frames are noodles in torsion. I have seen a frame flex so much when hitting the three wheel motion that the door couldn’t be closed once open until back on four wheels. Hitting things hard where the left and right wheels may hit something at different times causes the whole frame and bed to twist a little bit. Bed stiffeners won’t protect against this. The only thing you can do to stop the twisting is tube frame.
I have a nylon roll up cover that I’ve done some things with. Drifting on chunky dry lake beds and whoops and what not. It has lived but I can see it flapping around a lot in the mirror. I always roll it up before doing anything too wild. This style of cover is a lot more flexible so there’s not a ton of risk beyond the tubes that support it in the middle will dent the rails on the side.
