Thanks to Warren for forwarding this lead.  Perhaps it is more accurate to call these mini-jeep trains, but just outside Freeport, Maine, there is a CJ-5 and CJ-7 that still pull tourists in a tourist-trailer around the sand (which I think they call ‘narrated coach tours’).  You can learn more about them here.  I managed to find a few photos of them on Flickr.  It looks like there are two different coaches.

http://www.flickr.com/photos/the_west_wing/8152632437/

http://www.flickr.com/photos/7588183@N04/4858047781/?q=desert%20of%20maine%20jeep