I’d say not may have the “exact answer”.
1.5” seems a bit light, but may work. Probably fine under normal conditions but hitting a big dip or frost heave at highway speeds might test that theory. I’d shoot for a bit more. Nothing a sheet of plywood or 1” foam under the bed mat won’t cure.
congrats on the new rig!
I agree with your assessment would feel better with at least 2" of clearance. Another thing that might help if they are still available was shock absorbers between the camper and the truck. I think Lance had these. On mine I use a half inch plywood which has 1/4 inch dense carpet attached to it.
