Fifth wheel Travel on I-90 from Montana to seattle

Pulling a 40 ft. fifth wheel on hwy 12 is doable, however as I recall there is a sigh telling of 70+ miles of curves. Depends on how you like twisty roads. Interstate 90 is a very nice trip and many picturesque towns such as Kellog Idaho and Coeur d Alene Id. By the end of Sept. some Federal Campgrounds close. Do your research. We have traveled Hwy 200 also and it is a very nice trip.