Cabela’s has lots of great stuff for vans and RVs, including portable toilets, some portable showers, and tons of misc. stuff.  I wish they had a store in California, but they offer good mail order service, and free shipping for orders over $99, which you could easily spend buying essential stuff and bargain prices.  Check out the website:

http://www.cabelas.com/home.jsp?WTz_l=Header