Looking at buying a new truck for a camper, first time

I bought an F350 SRW with camper package in 2015, and an NL 9'6" QSE last week. Despite lots of due diligence and math, in big retrospect I can't help but observe trucks carry far less than expected/advertised, and campers weigh far more than expected/advertised. Wet+humans+dogs+stuff plus 2855 dry camper on a 3883 rated payload truck left me far short of the margin I had imagined back in 2015. Stunning and humbling.