I know this guy wasn't done with this, but with some work it could be cool (if you're into going to the dunes anyway). With a bunch of steel tube, a welder, and some creativity, you could make a really cool roll-cage / mad-max exoskeleton that would be pretty cool and make the car fairly indestructible.
Obviously the "usual" thing to do is build some kind of VW-based buggy...all the ones you see just for looks are generally a fiberglass body on an old VW Beetle chassis, and the full-on tube-chassis "sand-rails" usually have rear-mounted Beetle engines as well, just because it's a really cheap, simple drivetrain to use in one of these things. As for how a somewhat heaver, flimsier, FWD unibody setup would work out there...well, I dunno. If you reinforced the heck out of the unibody and stiffened it all up with the cage/exoskeleton stuff, you might get a vehicle that's awfully heavy to be out there jumping around.
OK, look at this:
Almost everything that is not required for the car to run has been removed i.e: Heater, Ac, It does retain everything needed to be street legal. The car is very solid with no flexing. I drove this car daily 50 miles per day on the highway to work and back last summer. It is really fun to drive and without all the weight pretty fast.
Does that mean he drove it as it sits with no doors, chopped windshield, etc. to work every day? That's how I take it, because he talks about it being street legal and fast with all the weight out of it -- wow, imagine seeing THAT cruisin' down the street.