Just curious, do you have much exposure to the rich history and the theory of reverse tricycles. Because there is a lot.
In the midst of Kach22i's laundry list he slipped in buildability. This is different to everything else on the list, and will determine the design as much as the aerodynamics. Are you thinking of something spun out of pure unobtainium, an aluminum monocoque with fiberglass fenders, or a donor Geo Metro and coroplast?
Here are some example that have been posted in Interesting Aerodynamic Cars (Mike Vetter's ETV, also Avion)
in the last 24 hours:
Here is my own effort. They could be converted to 3 wheelers; but I'd recommend front wheel drive with a reverse trike.
And the pure Template body of revolution (blimp shape), except with the equator lowered, in motor home size: