We drove that last August with our 40' MH towing the Jeep Liberty - coming from Yakima, WA. We took I-90 to 26 which was boring for us but an easy drive. Our main reason was to see the Palouse but all fields were plowed. Then you will have 95 into Lewiston which is a 7% downhill for 6 miles. It's very doable - many RVers drive it - but you should be prepared for 35-45 mph. Plan the night or two at Clarkston/Lewiston before tackling the rest of the drive. Hells Gate State Park was a very refreshing stop - lots of big shade trees on the river. We didn't have reservations but then we were there early in the week. Weekends require reservations. Then continuing on ID95 is White Bird Hill about 8 mi south of Grangeville. You'll have 8 miles of 7% grade downhill with 2-3 lanes. Again, you'll be going 35 mph. Those will be your biggies but again, doable. Just take your time. It's a beautiful drive!
Full-Timed for 16 Years
.... Back in S&B Again
Traveled 8 yr in a 40' 2004 Newmar Dutch Star Motorhome
& 8 yr in a 33' Travel Supreme 5th Wheel