To expand on Niel's comments-
Just as cars and planes differ in design because of ground effect, you will have consider the rest of the car when designing the wheel bumps, as the greenhouse alters the airflow and you cannot count on canned shapes to solve it for you. Jaray and Sason used the "2 part body" you drew for a reason- it's easier to manage and simpler to produce.
Do yourself a favor and radically simplify the design. Even the "Goddess" was designed around the simplicity principle.
Though it did end up drawing on Kamm's work. (Your last picture in post 52 reminded me of the DS's greenhouse)
Essentially, the more things sticking out from your car, the harder it is going to be to tune them for efficiency. If you really wanted to do that I would suggest making a third scale model and tuft testing it at high speed (I believe you'd have to do 40mph for 1/2 scale and 80mph for 1/4, so something in between those). You'd spend at least a couple hundred dollars if you wanted it to be clay (Check out Russ Simpson in Warren).
Anyway, yeah. Simplify this thing, and teardrop it in plan view too.