Regarding the Facetmobile project, someone could ask the club:
http://www.eaa292.org/
Wainfan once said that if you made a 4 passenger Facetmobile, it would have the interior space of a Winnebago. Just the thing for waiting out a thunderstorm at Oshkosh. At least if you had REALLY GOOD tiedowns. If I was doing it, it would have to be a Smoothmobile. I suspect that wouldn't be any harder to build.
Speaking of the V-173, I had a pet idea for a cartoon, square, ultralight version. A way of taking advantage of and making fun of part 103. I think, assuming it could be built light enough, that it would be safer than a regular ultralight. The top speed requirement would be met by using that calculation method, which only applies to square wings. The big props could both be driven by the same long belt, twisted to get opposite rotation. Got the idea for that from the hovercraft guys, some of whom run long belts around corners. The long belt, it is hoped, would mean the oscillating frequency was below idle. Another advantage is that you wouldn't lose just one prop and go into a spin.
I'm not sure if I'd enjoy it or not. The original idea was for a safe trainer, though I don't know how useful it would be if the goal was to switch to an ultralight glider afterwards. As shown, the landing gear is probably not great, and I think the props need to be larger to reduce induced drag. The little slanted bit at front was to house the engine. It's at a depressed angle for better visibility. When slow, this thing would have a high angle of attack. The engine was intended to be a 19hp Briggs vertical shaft, because it's lighter than the v-twins. Probably there are better choices by now. Don't they have oil injected two strokes these days? With the garage I have these days, I'd have to make it in three pieces or something, and I don't know where I'd keep it.
The real fantasy airplane would be a relatively high performance ultralight motorglider, intended to perform as much like a Carbon Dragon as possible, or maybe even better. Power would probably be a couple of electric motors mounted on the wing. I suppose, as long as we're being ridiculous, it would be nice if it looked like a classic old sailplane. Say a Slingsby Petrel:

or a Ross RS-1 Zanonia:

Yes, the latter is an American sailplane.
More practically, it could look like the Screaming Weiner, another American sailplane:


Ok, ok, for truly impractical, how about a Horten VI, which might actually be made safe these days, if enough carbon (and maybe boron??) was used.:

Of course it would have one or two tiny jet engines for launch. Apparently the real thing was pretty scary due to flutter.
I'd better quit while I have a brain.