Second Burgdorf but it is a little off your route unless you take the backroad which might be sporting with a loaded trailer - I haven't driven it for a while. On the highway is Zims hotsprings 30 mins South of Riggins, they have a campsite. Would have a bit of road noise as it is just off highway 95.
Zims Hot Springs - Zims Hot Springs
Or soak there and head to Last Chance campground which is 2 miles off highway 55 before you head up the hill to McCall, a good gravel road.
Ponderosa state park in McCall, has showers etc.
Or South to Cascade and check out the whitewater park? Several motels and campgrounds around the lake.