Malibu Divers is probably the closest local dive shop to any beach (right across the street from the water) and can give you updates on conditions - surf, viz, water temperature - as well as rent gear and provide a DM to help with So Cal beach dive logistics and go out with you. I've seen tourists stop in there late afternoon to rent gear for just one afternoon dive. You could always check out conditions before renting from them if you end up diving in MalibuGreat info. Seeing if we can get a DM for a half-day is a great idea! Any good dive ships near a good shore dive location you'd recommend?
If you're thinking of doing a late afternoon or weekend morning dive, you can probably find someone on here that might be interested in going out with you, or at least help get you started
Beach dives here are hit and miss, but can be spectacular. Unlikely you will have the same viz as you had in Bonaire. Timing a beach dive around tides also helps