US-191 from Vernal, UT to I-80 in Wyoming

We drove our Class C (not towing) from Vernal up to Grand Teton NP using 191 back in 2012. I know there were grades, but they must not have been too bad as I don't remember them being an issue.

The scenery on the route was great and we really enjoyed the tour of the Flaming Gorge dam.

I did it in a car and thought my arms would fall off. I don't think I'd want to do it in anything bigger, or for that matter, again.

Yup, an uphill climb north of Vernal. Switchbacks as noted. No real exposure though, so not like some mountain drives. Nice scenery around Flaming Gorge. Worth some time to explore if you have an extra night. Much cooler up there in the summer vs. anywhere around Vernal.

If power is an issue, might you disconnect the car and drive it separately up the hill?

Just take your time on the climb out of Vernal until you get to the top, it's a good highway but your big units will no doubt be going slow. After that, the route is no big deal, then beyond Flaming Gorge there's not much to see except sagebrush and antelope while you're in Wyoming.

From Vernal to the top of the pass..it's a pretty tough climb, but big rigs do it all the time. After that, it's all down hill, but in stages so it's not as dramatic as coming up was.
my mountain grade guide book says the grade going up out of Vernal is 5 to 8 % grade with 10 switchbacks...mostly 8 %. The road is wide with pullouts, etc.