I just got a piece of 3/4 inch marine plywood, cut off the last 18 inches, and then cut a few 2x4s I had lying around to fit, with 2 crossmembers. 2x4 are flat, not edge on.
Raises the camper about 2.5 inches, which was perfect for my F250. When I went and initially picked it up, it did rub the cab a bit with just a piece of 3/4 inch plywood underneath. The 2 by 4s laid flat lift it up just right for my 2016 F250. Ford has tall cabs.
The "platform" took all of 30 minutes to cut and screw together. Now it is a permanent resident in the bed of the truck.
