Hey skyl4rk, I like your ambition with the Versa tail addition, and would like to see the long-term numbers on it. One area of concern is across the rear wheels. The downward slope of the skirt can have the tendency to scoop air. This depends on the state of flow once it reaches that feature, but it is something that we look at a lot with solar car wheel fairing design. The
Aptera's wheel fairings can serve as a good reference, noticing the upward curve from the leading to the trailing edge.