Well, I must say, that helps clear things up for me a bit, as well...
I'm a completely new burner myself, having just gotten her ticket all of a couple short hours ago, and was actually planning on making a point of Burning solo this first time 'round.
As a friend of mine who's been burning for years now explained it to me, not going with a pre-established group actually lets you run around like crazy and have a good time figuring out what groups out there you click with, what groups don't work for ya, etc. There may very well be some group that you *think* you'd jibe really well with, spend all kinds of time petitioning to get into, etc. only to find that you and them totally aren't the right fit for each other whatsover...and that would then make your experience not nearly as worthwhile as it coulda otherwise been.
Personally, I'm seeing my first time as a truly self-exploratory kinda thing- I'll go, see what Burning Man's all about, and then see what sorts of groups work well for me once I'm there. But, going with a large group would wind up taking away from the flexibility of doing this, since you'd wind up more than likely at least spending a large chunk of yer time with them.
Enjoy the whole experience! I'm so excited I can hardly wait! 57 days seems like way too long a time to wait for such an incredible experience!