I curious as to why you would bother building something to sit in the bed? Why not just use a ramp and load the sled into the bed of the truck? I get it if you have a silly little truck but the answer to that is to own a full sized truck... I have been hauling my sled in the bed for years and never felt the need to build a bunch of junk because I couldn't figure out how to just use a ramp. Even when I had the Raptor with the 5.5 ft bed I still didn't have any problem loading and hauling my sled without the need for an in bed sled deck. Just seems redundant.
My carbides were destroying my bed liner.
I threw down a few 2x8's with a sheet of 3/4 plywood to keep from destroying the bed floor. Also gives me a place to slide the ramps in rather than having to strap them or listen to them flop all over in the bed.
But I'll agree with you on real trucks. Crew cabs with 8' beds are the way to go. I have 3 now.