Have you taken any measurements to determine the gains from that tailbox, Ecky? I'm curious to see if it increased your cruising speed and top speed.
I've come across the Quattro during many online searches. It is an interesting machine and I'm sure Mochet would have been floored had he been alive to see it. I suspect that it's overall aerodynamic drag is similar to that of a Quest velomobile.
However, I'm more partial to the commercially-produced QuattroVelo:
https://www.velomobilcenter.dk/galleri/velomobiler
That is the sort of shape that modern entry level sportscars should have.