In Hang Glider Weekly Magazine, Vol. 5, No. 2, page 2, there was an ad from the Thompson Boxmoth company. I had featured two large photos of the
Boxmoth on the cover of the issue.
(July 21,1978, issue) to tease a hang glider version (without motor). To date: I have not seen such a HG. But one day at Dockweiler, such might occur.
Here below is a clip from a current web page:
Thompson (Richard) Thompson Aircraft Co, Philadelphia PA.
Thompson Boxmoth [N64492] (undated magazine clip via Warren Drake)
Boxmoth 1972 = Home-built 2p tandem "flying box-kite." Thompson expanded his experiment in powering a boxkite with a model airplane engine into full-size reality with twin vinyl-covered aluminum-tube frames and a 55hp snowmobile motor and a prop. Did it work? Test flight, reported in his own words, "Great stability. I was 35 feet off the ground before I realized I had taken off!" FAA reg [N64492] issued 3/30/73, seen as still valid in mid-2007. Marketed plans for $75.
When will a hang glider version of the rhombic Boxmoth sans motor be glided at Dockweiler?
I imagine someone might want to
airfoilize the wings to other than non-flat configuration.

Notice the motored version using the triangle A-frame for landing gear; W. Simon in
1908 had the triangle control frame without wheels on a foot-launch battened flex-wing hang glider, and used stay wires that became flight wires as we use today on so many hang glider. Since W. Simon hung from the keel as we often do today, had he stumbled and whacked, then his basebar would also have been a landing gear, and he probably would have wished he used wheels or skis.