Shhhhhhhhhhhhh. You're giving away all the resident secrets! That's what happened to Pioneer Pass; we use to use that as a hidden cool getaway from the heat until people discovered it. Now you go there and packed minivan day users are parked in the campsites. :(
But, yeah those MT Graham campgrounds are an escape from the heat and fortunately, due to the switchbacks and tight maneuvering, it keeps many RVers from going up to the upper campgrounds. I went to Riggs Flat in July and the place was empty. If you can, push up higher to one of the other campgrounds (the roads are normally well maintained up to the telescope) and maintained up to the lake. It may appear scary but it's worth the trip. Again, no huge RV's to worry about except those stuck in a ditch or against the trees because they ignored the size rule. :)