Need good advise.

[Helio]

Have Rapture 39 foot toy hauler. Probably totally loaded weight would be around 22,000 pounds.Looking to update our pickup. Pulling camper with a 2002 Ford 350 pickup (Manual shift) Want to update and also need a automatic. Want to do alot of mountain camping, Do we need a 350 or should be have a 450? What are the thoughts of a dually? Does Ford handle better than the DuraMax Chevy?