When I've done that route, I parked at the OBFRT end and hitched a ride back when time wasn't critical.
Your way would be a little more sure if you can time the hikers bus or YARTS early enough.
Otherwise, hitching is the way I got back to my car each time. Might not want to start the hike hitching, since it's uncertain how long it'll take (that's why I left my Jeep at that end).
Your mileage may vary, but I've never been able to get to the top of El Cap on day 1 (but that may be because i picked up my permit the same day, so usually didn't get started until mid-morning... or I'm just a slow old guy.

).
My fav camping spots along that route:
Top of El Cap
At the edge of Eagle Peak (there are some campsites very close to the top).
The first legal camping spot above Yosemite Point. It has great views in all directions.
The top of North Dome (there are several nice spots jsut short of the high point), but be careful climbing down to North Dome... the trail is a bit tricky.
Tip: Pick up your permit at the Big Oak Flat entrance. Usually not as busy as the Valley Wilderness Center.