Lots of beaches to detect. Whether it will be "good" beach hunting is hard to predict. Bay side camping eh.....hmmm.....probably J st. marina area in Chula Vista on San Diego Bay, or boondocking it on Fiesta Island in Mission Bay. No good beaches by the J St. bay campground, but, several nearby on the ocean. Fiesta Island would take you over a year to detect. Ton's of junk there.....good stuff too on occasion. Lots of other beaches on Mission Bay that can be good. Miles of ocean beaches too a short drive away. PM me if you need specific areas along with where you are actually staying.
From south to north:
1. Imperial Beach. Very long beach starts at the Tiajuana River. Mostly locals and Hispanic.
2. Silver Strand. Lies between Imperial Beach and Coronado. Sparsly used except around the State Park. Navy trains frogmen there (Seals).
3. Coronado Beach. If you are looking to find "high end" objects use the detector in the vicinity of Hotel del Coronado. Gets pretty sparse the farther north you go.
4. San Diego Bay. Shelter Island has a tiny beach about 100 yds long. You might find some fishhooks there.
5. Pt. Loma/ Sunset cliffs a couple of small beaches mainly used by surfers.
6. Ocean Beach. Lots of people frequent this place, kind of low rent (that's funny), but for San Diego it is the place for "hippies". Probably pretty trashy.
6. Mission Bay. I agree about Fiesta Island. Lots more small beaches. I would head to Crown Pt. or one of the beaches in Mission Beach on the Bayside.
7. Mission Beach/ Pacific Beach. 3 miles packed with tourists. Start at the Roller Coaster, work your way north.
I wouldn't go much farther north than the pier.
8. Tourmaline. Mostly surfers, dog walkers and joggers.
9. La Jolla. Pronounced: la hoy ya
A. Wind and Sea Beach. It may be your best place to hunt. Small beach but packed with rich people. You will have competition. Go late or go early.
B. Marine St. Another small beach (300 yards) utilized by rich people's kids. Try this one also. It is a short walk from Windan'.
C. Children's Pool. You'll have to fight the pinipeds. Tiny beach (50 yds.)
D. LaJolla Shores/ Scripps Pier. Start at the Beach and Tennis Club ( tennis bracelets anyone?) About a half a mile of more rich people.
La Jolla is worth it just for the great scenery.
E. Blacks Beach ...take off your clothes and enjoy the sun. That's right, nude beach starting about 1/2 mile north of the pier.
AND THEN THERE ARE ALL THE BEACHES IN NORTH COUNTY.
Be warned: Go early. Parking gets real sketchy after 10:00...unless it's overcast or raining.
Have fun. Eat at any "Robertos" or "Albertos" Mexican take out restaurants. Great food, excellent prices. I think these guys were cousins.