A primary problem you will have is finding a 5th wheel toy hauler that doesn't exceed the payload of your truck. When I did some research there were only a few that worked with my F250, and they only had 10' garages. I would recommend you research your truck's payload and what it weighs fully fueled with passengers and whatever else you carry. Then subtract that from its GVW and that is what you can have as a pin weight. It will surprise you how little that is.
Don't rule out a TT TH, as that will no doubt fit your truck's ability.
2000 F250, 7.3 PSD, 6 speed manual, CC, SB
2013 Northstar TC800