I've always been more of an Isetta fan, myself. :gig:
I've always wanted a Messerschmitt, but never could find/afford one.
But back on topic:
You have more motorglider designing time than I do. If you were to attack this particular design challenge, a part 103 legal motorglider with minimal self launch ability, what kind of performance do you think is possible for a plane that can be built by a reasonably competent do it yourself type craftsman? - and for the cost of a new 4 wheel ATV.
What would it look like? The American Eaglet/Baby Bowlus formula seems to me to be a reasonable starting point?