After for lurking around for a while, I may have decided to pull the trigger. I am looking to buy a 2016 Dutchmen Denali 307RLS. I can tow with the F250 without being over weight (on the higher side, ...
If it's a single rear wheel F350, I would go for that.
Unless you do a lot of off roading (for which an F250 or F350 is a horrible option anyway), not much benefit in going 4x4. Realistically, a 4x2 with limited slip and a 5th wheel on the back will have a ton of traction.