I've done a lot of touring in central-southern california. After a certain point, many campsites claim they don't have HB sites. The official line is that they are trying to "discourage transients." Bummer. I can confirm and recommend these sites if you pass them.
Moro Bay - (you're by a golf course, but it's not too bad.)
Refugio - MUCH better than El Capitan site. You're about 20 feet from the water. Easily the best HB site in Southern CA.
Carpenteria - Sort of ghetto-ish...not scenic...the times i've camped there I've had questionable neighbors
Leo Carillo - Nice. Tucked away off a trail. Pretty quiet.
San Clemente - has a HB site...nice but nothing special.