So, you are camping and you want to unload your truck camper

When we had a wood frame tc, I made 4 cubes with 4 sides and the top solid out of 3/4" plywood. Glued and deck screwed them together. They were 12" high. Each ones width was 3/4" smaller than the largest one. The largest was 12" wide and each fit into each other. They did not take up too much room in the camper. They were solid as a rock with the camper on them, and if I needed to do any maintenance with the jacks one at a time at home, they supported whatever the jack did.