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, ...
Having had both (2004 RAM 2500 4x4 shortbed and now a 2006 Chevy 3500 4x4 longbed) with diesel plants, I would not bother with a 2500 given the relatively small difference in price.
You can always tow below the limits on a 3500, but not (comfortably) above the limits of the 2500.