Personally, I'd find a hard-ish compound all-terrain (AT) tire, or get some kind of run-flat insert to put in an AT tire. (maybe have new centers welded into H1 runflat rims) There's obviously no way to change a flat out there. If I was running normal AT tires at 20-30mph I'm not sure that I'd want less than 20psi, probably around 25-30psi. You risk popping them the higher the PSI, but you risk rolling it off of the bead at lower pressures.
I have a few pics of Bob Land's VX, and the tires that he used. They were not off-the-shelf tires. Bob told us that he had them custom cut, and were a very hard rubber compound. The ones on the VX in the pics below have a race on them, and I had a hard time telling them from the brand new ones in his shop.
http://tad.grosvenor.org/gallery/MoabMay2001/a22_19A
You can see the size here: (7.50 R 16 it looks like to me)
http://tad.grosvenor.org/gallery/MoabMay2001/a24_21A
Here's the tread that he ran on his Amigo:
http://tad.grosvenor.org/gallery/MoabMay2001/a21_18A
Keep us up to date. This company has an entry as well:
http://www.mitre.org/news/digest/adv...hallenge1.html
A group from Florida entered a 1993 Trooper last year.
http://cimar.mae.ufl.edu/teamcimar/g...2004/index.htm
-Tad