Storage in California
Storage is hard to find. If you must, one of the best options for storage around the country is at the KOA's. See Koa.com for info on locations. I use the KOA in San Diego (Chula Vista) for many months at a time. It cost me $80/month for my Sprinter van or trailer. That is about as good a price you will ever find.
There would be many other options though if you tried. KOA(Campgrounds of America) is just easy and secure in my opinion.
Good luck, I am thinking of shipping my Sprinter van to Buenos Aires from LA. Already did it with my moto but by air, I left it down there and will return to chase the Dakar.