Declo, Id. City of Trees RV Park is right off 84 on the river. There is an rv park right in Heyburn. Heyburn Snake River RV Park I think. Nice and not a bad price. Check RVparkreviews.com. Lots of good info there.
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 ...
US Hwy 95 is a good route and goes thru Pahrump Nv. Access from Pahrump is easy and there are a couple routes that go to Death Valley. You can also access DV from Armargosa Valley. The Route 247 (I think) by Death Valley Scottys Castle is closed b...