I used to fly out of CRQ and OCN about 1.5 years ago....

Check the A/FD for the Frequency for "Longrifle Range Control" at Camp Pendleton Airport. It is a VHF frequency as I recall. They are the controlling agency for R2503 and will be able to tell you whether they are "hot or cold". Also check the top of the San Diego Sectional or TAC Chart legend for applicable altitudes. I do not recall specifics (and do not have the chart readily available), but I remember something about R2503 A & D not being a factor as long as the coastal route is flown above or below a certain altitude.