Hmm...only ones I know of that are right in SD are Campland by the Bay and Mission Bay RV Resort (or something like that). Both in good locations, but basically, they're like parking lots.
There's an RV park right at the beach in Coronado...again, your in an asphalt parking lot, but it's freakin' right on the beach!
I've heard that Chula Vista RV Resort is nice, but I've never been there. Prob about 15 minutes south of the city of SD.
Or, 30 minutes north of the city, San Elijo State Park, or Carlsbad Campground (not sure of the exact names of these 2 places. They are both on a bluff right above the ocean, so great locations, but you'll be parked in an asphalt parking lot like all the others.
Traffic in and out of the city can truly suck, so you might want to pick the place that's closest to where you need/want to be.