Umpqua (tokatee) hot springs are not too far from crater lake. Great place to have a relaxing dip. It's a clothing optional sort of place, so don't go if that bothers you. Although, there's a decent chance you'd have it all to yourself on a wednesday night. There are several pools of varying temperatures, and one of the best ones has a roof over it as well.
Also, a beautiful hike from the parking lot along the first mile or two (heading north) of the Umpqua trail, known as the Dread and Terror section. It's easy hiking and very pretty. Water springs out of the hillside (cold) all over the place and flows into the river. You can drink the spring water.
The hot springs are located at 43.295035,-122.365873 Google Maps Link
There are beautiful tent sites along the river there. But with the rig, i'd just drive around and find a nice spot to pull off. If you keep driving past the hot springs, you'll eventually come to some clearings that are pretty decent sites. Haven't actually stopped there but have seen people camped there. I don't think they're on the river though. The area is free of snow down at the elevation of the springs.