you definitely want to get the Mountain Directory Books by R & R publishing. I just bought mine a few weeks ago and the shipping was very fast (there 3 days later).
There is one pass I know for sure that isn't mentioned in that book though. It's Piney Pass between Victor, Id and Palisades, Id on hwy 31. Not a big pass though. In Yellowstone, going from south entrance up to Old faithful there is a small pass. Some campgrounds have restrictions on vehicle plus TT total length. So be aware of that too.
If you enter Jackson from the south, you'll be ok as long as you do not go from Jackson to Victor, Id. That crosses over Teton pass with 10% grade, and little guardrails. That's hwy 22 so stay clear of that.
Hwy 26 is ok I think, but I'm not sure about the colorado areas. There is one pass on I70 that is kinda scary, but I did it in a blizzard, pulling a uhaul, at midnight, next to a semi almost running me over and I was 22 years old. We were the last ones to go over it before they closed it behind us due to the storm. We should've waited but I was young n stupid. Point is, you can do it but check the Mountain directories and atlas and be careful in weather.
The directories will tell you the speed limit, size of road, how many miles the grade is, and if there are hairpin turns. I steer clear of anything with 35>mph turns. Getting my RV to that speed going downhill hill makes me nervous, but I'm just starting out driving these things in an RV and not an SUV myself.
Google maps doesn't really help me other than to see the kind of turns the passes have. It's too hard to tell if the grade is steep or not. Googling the pass names and asking on these forums have given me tons of info.
Good luck!
