We are at Glacier National Park right now. Yesterday we drove over "Going to the Sun Road" in our pickup. We are staying in Hungry Horse, outside the park in one of the nicest RV parks we have
ever stayed in: Mountain Meadow. There are many parks nearby. There are also some campgrounds inside the National Park, but I am not familiar with them.
There is NO WAY you could tow a trailer or take a motor home over Going to the Sun. The length limit is 21' and width is 8'. There is some road construction going on, but the delay for us was less than 5 minutes.
I'll be glad to answer any specific questions if it would help.
I would highly recommend a visit Here are some scenes from our drive yesterday:
http://dw4u.net/Glacier/Glacier.html