Just trying to help. People apply the template to everything. The thing is the back 70% depends on the airflow set up by the forward 30%. You can't just tack it onto the back of some arbitrary form. Mair starts with an extended body (fineness ratio is your friend) with a circular cross-section. There is (somewhere) some middle ground, hence the wind tunnel rules over theory.
I like the Tropfenwagen, it's shaped like a submarine conning tower. I tried combining several aero-forms into one:
This would need serious filleting and tweaking, but could accommodate specific internal space requirements.
You could lose all the [upper] taper and optimize the sides. Here's a study of putting a back window like the 1948 Studebaker Starlight coupe on a Beetle:
