Save yourself the hassle. You'd be better off nixing the 5th wheel and getting a lighter weight bumper-pull trailer. Or biting the bullet and getting a 2500/F-250 to handle the 5th wheel without over-taxing your truck. Personally, I won't tow anything through the CO mountains, or any mountains, without a diesel doing the work. Gassers have to work way too hard to do what diesels do with ease.