It was one of the units manufactured by Don in Watauga TX. I've seen his Craig's List ads but this was my first personal encounter. This one was nicely built with a galley and air conditioning. Siding is Filon or FRP; roof and hatch aluminum with a diamond plate rock guard; built on a Ironton or similar trailer.
I believe it is this one:

More production pics here: https://www.flickr.com/photos/51728468@N03/sets/72157634379804457/
The builder's website is here: http://www.ez-toad.com/
The owner has visited here but has yet to post, so welcome Wendy and encourage her to join the party.