One other consideration concerning carrying "stuff" in the truck bed is the air turbulence back there when hooked up. I once lost a 42 inch wooden pallet that I was going to use as a porch when I arrived at the campsite. Arrived at the campsite, where is the pallet? No damage to the trailer or truck, must have vaporized?
A friend tells of buying a truck with a molded plastic bed liner. After someone else mounted a hitch in the bed, he went to pick up his new trailer and had the entire bed liner lifted from the bed by the negative pressure back there.(they had cut slots in the lining for the hitch rails)