Thickness of flat bed

Measure the distance between the top of your frame and the top of the cab on your truck, then measure the distance from the bottom of your camper to the bottom of the cab overhang, make sure the floor height of the deck is so that the camper doesn’t stick up too high over the cab or sits on the cab. I used checker on the floor and a rubber mat on top of that to keep the camper from sliding around too much, Check out Alum-Line’s web site, they will make a deck out of aluminum and will mount boxes on it for a reasonable price. If you are taking off a truck box, you will notice the frame is not flat like a cab and chassis. Run a straight edge along the length to get the proper height as you will have to block up the low areas. If you use flat plate stuff tends to slide around on the deck if you are going to haul with the truck when the camper is off.