I lived there a few years ago for a short while. Seemed like it was always an issue. I would park with all the windows rolled down, took my reg/ins. cards w/ me, had much better piece of mind, never a problem. A friend would do the same but also leave a dollar bill somewhere in the car just to know if anybody was in there. Sounds kinda crazy if you've got a really expensive ride, I know.
Crash Pad might help with luggage storage, or a free day pass/week pass at the YMCA - big lockers, take some locks.
Mostly country kids looking for petty theft, not grand theft auto.
Enjoy the T-wall, awesome place!
Good luck, carpooling in is a good idea too. But yeah, camping/hanging out there for days. Ooooooo, tough one.