Not much to ride out there unless you are willing to drive a bit...
Pala pool/pipes, Carlsbad(at night), Real Ride, San Clemente, Clairemont YMCA.
There are more but they aren't worth your while or you'll never be allowed in.
Also, the Corona parks and Fontana if you are willing to drive a little farther.
Pala and Carlsbad are probably your best bets but Pala is just an old pool and steel pipes(if you are into that) but I wouldn't suggest going there alone... especially on a scooter and Carlsbad does not allow scooters and it is built right between a fire station and a police office despite all that I've only been kicked out once and it was one of the few times I went there during the day so just go at night and they will never say anything. The lights shut off at 10PM.