Long Beach has the Claremont catamaran Ramp - HERE.

You can drive right down to the circle on the beach and set up the boat. Attached trailer parking for the day is $12 (cash or debit card). There are bathrooms right there, and it is a short walk to 2nd street - the cat sailors favor Taco Surf after sailing.

Carry your PFDs and you'll be fine with the Harbor Patrol - launch and return through the orange buoys to avoid the many kiters along the beach.

I live a couple of blocks from there - let me know when you'll be around and I can help you step the mast. :-)