The info I've got indicates that your rig weighs in dry at around 4,800. That's not that much more than our 67, which weighs in dry at 4,650, and which we tow in the mountains at elevation with an F150 with the smaller V8. You'll probably be ok, depending in part on how much stuff you decide to carry along. Be sure to use adequate weight distribution and sway control.
Check this thread, to which I posted a PDF with weights, etc.