Cab clearance

Hi everyone. I have a 2000 bigfoot 25c10.6 that I used to haul on my 95 standard cab f350 , it would haul it but it was over taxing the truck . I recently bought a newer f450 to haul this beast .... Well when I began to load it on the truck I noticed the cab lights were far to close to the bunk and would not last if I used the camper without adding some plywood to raise the height a bit.... Fast forward , I had to add about 4" to get enough clearance . My plan is to use blue board sandwiched between ply as well rubber mat on the top and bottom .
If anyone has had the same clearance issues please let me know and post pictures of what you did to correct it. Thanks JW