Ford Tow GuidesLook at page 10 of the 2014 where it talks about truck campers and you can see the difference in cargo capacity.
If you are just buying the truck to tow a camper with I'd look at a long wheel base for a nice ride. More capacity than I think I might need to two reasons. 1- the less the truck has to work to do the job, the longer it will last. 2- it's more fun and comfortable to drive a truck that has sufficient power for the job. Engine brakes are wonderful in the mountains.
Also the leg room of a crew cab is wonderful and it's great to have extra room to carry things in the cab. Folding a rear seat up can generate much useful and needed space at times. Not to mention room for passengers when friends go out to eat.
If you upgrade, a 14,000# GVWR is common on new 5'rs and that's a 2,800 - 3,000# pin weight plus the weight of the hitch. If you add a generator or washer/drier even more. By the time you fuel the truck add the spouse and stuff for the trip your 4x4 super cab F250 is going to be over GVWR of 10,000#
I'd buy the F350. If it's just for towing a camper I'd look at the DRW not only for capacity but stability.
At 7-10,000 miles per year and add a boat your at 11,000# plus maybe a new 5'r, I'd say diesel. A new 5'r plus boat your looking at 24,000 or so GCVWR.
Good luck with whatever you decide.