Is towing w/SUV in mountains unrealistic?

[FlowerPower]

Hi all. New to the forum as I'm looking at a couple of different used TMs (2619, 2720) and wondering if I'm in dreamland when it comes to driving from IN to MT/WY/ID in the fall. Other trips would be less arduous and at much lower elevations.

I have a Honda Pilot (4500lb TC) and a GMC Sierra 1500. The Pilot is more comfortable to drive long distances and my first choice. After reading some posts on the forum, I'm more confused than ever. If I use the Pilot, I'd absolutely get a WDH. Not sure if I'd need WDH for the truck?

This would be my first travel trailer and want to make it an enjoyable experience, not a regrettable and expensive nightmare.

Thanks for any thoughts and tips!

Kathy