nomadist, if I may suggest. Instead of dolly wheels, go with a frame to frame roller. It won’t miss the high spots on irregular grade surfaces. A dolly wheel may be at a low point on the grade, or fall into a hole.....doing you no good! Our 5th wheel has a full side to side roller, our class c roller is only about 3 ft wide, but still offers an advantage over dolly wheels. You have a lot of rear overhang.....get the most that you can get to provide as much protection as possible! Maybe even several types of protection.....lift, roller, air bags, ect! memtb