Beartooth Highway

X2 - Worked on that highway and drove it many times about twenty years ago, the curves and grade going towards Yellowstone are pretty hard in an RV of the size you're proposing. Going downhill towards Red Lodge from Yellowstone takes some good braking skill too. If you've driven many mountain highways you may have enough experience and confidence to do just fine, but I'd advise not driving it.

I wouldn't!