There are several dispersed campsites along the lakeshore located just before and beyond Upper Payette Lake Campground. Sites have no amenities and are often difficult to access with a big RV as the ground can be wet through most of July.
Take the Warren Wagon Road (Highway 21) out of McCall and travel 17 miles up Warren Wagon road, go left on Forest Road #495 at the sign marking the campground entrance off the highway.