I did not hire him to come and shoot nude photos of me for Donny on the thread below.  

Your best bet is to go east to Cuyamaca state park. As long as you're off the beaten path enough there won't be anyone around to bother you.

Caveats include it being pretty hot out there this time of year, and you'll have to hike in and hike out. This can get tricky when you're chasing light as the sun goes down, so give yourself more time than you think you'll need to get out and bring a couple nice flashlights.

 
As others have said, Blacks is a no-go because it's too small and also not really that spectacular looking. If you're dead set on a beach location, http://www.californiabeaches.com/beach/san-onofre-state-beach-nude-area is about the best in your driving range.  

 
Personally, if I'm shooting nudes I go to Malibu. There are a few beach locations that rarely have other people there, and they're like 10 minutes away from hiking trailheads that go out to some great oasis-y cliff diving locations. I don't know that I could tell you exactly where because places like this don't exactly have addresses, but if spend some time up there you'll likely find plenty of places.

Is no one going to step-up and help? Most all of you locals live on private estates in Coronado, La Jolla, or Rancho Santa Fe.  Surely they could do a spot of nude photography in your backdoor...?

Dixon Lake

You must be discreet, but if you get there at the right time no one is there.  Absolutely beautiful in the early a.m. & they have hiking paths that are a sure bet.  In my opinion it is one of S.D.'s hidden gems.

Nudist resort in the high desert. Maybe a cost to enter but no hassles. Very stark landscape and safe...