I was told that too... a nice drive over Teton Pass... the Ram Cummins is absolutely up to it. I like scenic, that's the whole purpose for us in RVing. This is also where the Aisin really shines. Had so many advise us NOT to take that route, and aside from the great view, it was cool challenging it. Make sure your trailer brakes are in optimal condition.
For us, managing speed is critical... when we traveled US191 we came to a complete stop for about 30 minutes while a heard of sheep were hearded across the highway. As long as length or height isn't restricted, we go.
When we plan a trip, we build an itenary of places we want to travel to, plot routes, and stops to include reconstitution days. I had ankle fused and it doesn't like inclines, so on physically demanding visits, we add a day of rest.
Anyhoo, planning routes and seeing America is fantastic... you'll figure it just fine.
Cheers, Ron