For the posters who think Zephyr Cove will be too crowded in August: Everywhere up here will be crowded. Also, Camp Richardson has many activities and a shuttle to take you to some of the more popular places on the south and west shores, so you could leave your RV parked. Both of those resorts have beach access, motorized water sports, horse back riding and a slew of other things. It's been mentioned that one poster found these 2 beaches 'rowdy'. It would be interesting to find out what they think 'rowdy' means. Is it boisterous behavior? Some people who use courser language than them? (sorry, but that's everywhere) Or, is it a case of 'You kids get off my lawn!'? It's a beach, for heaven's sake. There's no nudity allowed, they're family resorts, and frankly, other people can have a good time in a different way than you and not hurt anyone.
And, yes, if you can swing a camping spot inside Yosemite, you should do it, and use their shuttle system, too. See what you want to see. And, if it becomes too prohibitive to drive a monster sized RV around, consider the option of driving a car, and staying in the 2 places you really wanted to see. Don't let folks discourage you from what you want to see because of their concept of how they would spend their vacation.