Well now - there is camping and then there is camping. Seeing as you have a HR motorhome this is an RV site, you are probably talking about "fancy camping."
Bagby Hot Springs has a primitive campground near the trailhead, but I wouldn't t try to put a HR into it.
Kahneeta on the Warm Springs would work. You may be able to camp at Paradise CG on the McKenzie and travel a few minutes to Terwilliger (Cougar). Givens Hot Springs in Idaho would fit your bill. Some of the hot springs in eastern Oregon have primitive camping spots.
2003 Monaco Safari Trek 2810
Coos Bay, Oregon