If the OPs issue is like rickjos pics then yes it appears the outside rails of camper aren’t able to be supported by the bed structure.
After maybe 20k miles of hauling an AF860 in a short bed (similar stresses I’d imagine), the camper, early on, dented the very rear of the truck bed floor on both sides under the edge of the camper. But the camper seemed to “settle in” there and not further damage the truck bed.
Bottom line, TCs aren’t the “distributed load” on the bed floor that they would appear to be. Taking the bottom cover off of mine to repair a tank support piece confirmed it. The bulk of the weight is transferred to the truck on the 2 outside edges.
If I got a new truck and heavy TC, I would absolutely consider a layer of plywood or foam if I was concerned about damage to the truck bed.
Pickup beds ain’t indestructible. That’s why flatbeds, hauler beds and dump boxes are made. For heavier use than a pretty truck bed can handle.
With TCs being a unique and very small % of end users of pickup trucks, it stands to reason that trucks aren’t specifically designed to haul TCs.
