That is my favorite stretch of paved road in Idaho. Amazing scenery and history on that corridor. Read "Undaunted Courage" before your trip for the Lewis and Clark history.
My TV and TT are over 50' long and it's not anywhere close to an issue. Many semi's use the road. The pull up to Lolo Pass is good one, but the corners limit speed more than the grade itself. There are passing lanes and it's not too long.
I like staying at the Powell campground next to the Lochsa Lodge and walking up to the Lodge for a nightcap and huckleberry cheesecake. It's one of the few times I am excited to camp in a campground. I pulled my 50'+ setup thru the RV loop with ease.
If you are heavy on extra time I highly recommend the walk into Weir Creek Hot Springs.
