If you are set up for boondocking I would suggest a couple of nights on the bluff at the visitor center. Not much better than the sunrise view at the"Mittens" overlook.
Gouldings is about the only other option, if you wast hookups. If you stay there you should do a little hike up to the natural bridge just above the GC. Keep an eye out for rattle snakes.
Unless they have done a lot of road work I would not try to drive any type of RV through the valley. The paid tours are well worth the price if you have a good guide (some are not too personable). You see places you can't access, otherwise.