Hi Steve, I don't know of any courses like that near me hear in SoCal but you might check out this link to Lat. 38:
https://www.latitude38.com/
and check their ads and
crew wanted section. What I'd recommend is that someone here on CF, who knows a good
delivery skipper on the west coast, can get you in touch with him/her. (I know a good one but he's retired from delivering) Then if you can get on a
delivery from north to south (which is less demanding than south to north), during the summer or fall, that could be a good way to get some sea time and really learn a lot. To me that would be much smarter than trying to sign on with an owner looking for crew, unless you REALLY know the qualifications of the
skipper or owner and you know the
boat is in really good shape. (It is just as important, if not more important, for potential crew to interview a skipper. And a good skipper will want to interview you too, and an experienced skipper will probably be able to tell in less than two minutes if you are a good candidate.) Do you know how prone you are to sea-sickness? Are you the type that stays calm in the face of adversity or discomfort? those are two good certifications to have

Good luck to you!
Welcome aboard, by the way.