What kind of a club are you looking for? Escapees, FMCA and Good Sam are nationwide organizations with local chapters. However, most chapters don't do anything more than organize campouts a few times a year.
If you're looking for places to meet up with other RVers, winter is the snowbird season and there will be lots of activity in and around the Colorado River area. For example, the RV Forum will be holding a week long rally January 19-26 in Quartzsite and you're welcome to join us!
Hi Melissa and welcome to the forum. I was born and raised in the OC, and lived there most of my life. You are close by to one of my favorite places to RV. Crystal Cove state park is not far from you. Sadly, we don't fit in there anymore, as they have a 38' max limit.