Hi Lance,
Glad to hear you've been doing a lot of reading . . .
Joining a camp is not a must. You're going to meet people everywhere, and will have neighbors (always introduce yourself!) and can visit theme camps all day long if you want to. There are lots of pluses about groups, but some of the nice things about going solo are that you don't have to pay dues, or labor however much a theme camp might want you to, and there's no drama unless you like to argue with yourself (I don't judge).
However, if you crave the theme camp experience, I believe there are still some camps accepting new members in the
2011 Theme Camps forum a couple of blips below this one. There's a post at the top with some helpful tips about what to do, and what not to do. Then look at some camps, & email a detailed little letter to the ones whose goals appeal to you, and be ready to tell them why they'll want you, and why you like them. (Theme camp representatives don't come to the
Introduce Yourself forum very often.)
If you're looking for a rideshare from SF, post on
http://rideshare.burningman.com
and click Regionals on the main site homepage to look at regional lists. Or google "Green Tortoise San Francisco"; they have a 5 day trip and provide food, water, transport and shade (BYO Tent, etc).