I just helped a friend move and their reservation got bump-upgraded from a cargo van to a... tall cargo van?
It seemed the perfect amount of space for BM car-camping, with no need to stoop over as you move around inside. Plus, there's lots of hand holds and other holes punched into the metal for anchor points for hammocks, curtains, etc.:
The rate was $65/day or so, plus taxes, with unlimited mileage in NV, CA, and AZ. I asked the attendant if they allowed their vehicles to go to Burning Man, but she'd never heard of it. When we returned the vehicle, I asked a different attendant how they track if you've gone outside of the tri-state area and he said it was based on mileage. I conclude this means it doesn't have an onboard GPS that reports off-road excursions, such as going onto the playa.
Also, it was a hell of a lot less stressful to drive than a 16' box truck! Easier to lock, easier to climb into, and I expect easier to clean. The one we drove only had 6,000 miles on it, so I think they're new to the Enterprise fleet.
It makes sense if you don't think about it.