Standard heigth of truck campers above the truck bed?

I am still trying to add enough material (plywood/foam/planks) to get my Lance camper a safe 3" above the cab lights on my 2013 Ford F350. A 3/8" rubber mat and a 2" thick sheet of pink insulation foam is STILL leaving the front of my camper a mere 1" from my over-cab lights. Doesn't the height of any bed platform that the camper rests on eventually get to an unsafe height? I'm looking at a 4"+ platform before I clear the cab-lights by 3".
Do all truck camper brands build on a standard "height" from the bottom to where they hang over the sides of the truck bed? It would be nice to see truck campers built higher to adapt to the cab heights on some of the newer trucks....like mine.