And for anyone interested in 2wd rentals, Campervan North America rents Sprinter and Transit Connect based Sportys out of Bozeman MT, Las Vegas, and Austin TX locations. Given their fleet size (16 Sportsmobiles) and presumably lower maintenance for 2wd units, the rates are significantly less, about $700/wk for the little Transit Connect campers and $1500 - $1800/wk for the RB and LB chassis Sprinters.
We rented one of their two-person RB Sprinters for a week long Grand Circle tour out of Las Vegas earlier this year and found the unit to be well maintained and low mileage. They seem to refresh their fleet every three years or so, selling the used units while still fresh enough to fetch sufficient replacement costs.
I would highly recommend them for anyone wanting to rent a 2wd Sportsmobile: