Airstream are pretty robust, but at 30', the rear overhang on mine might be problematic. Perhaps a 19' Bambi or maybe 25' model.
The tires AS typically uses are Goodyear Marathon ST tires. They suck. I'd definitely replace them if I were going off road (I put Michelin LTX M/S LT tires on my 30').
Anyway, there might be some ideas here:
www.expeditionportal.com
And here:
http://www.kimberleykampers.com/