I'd never have guessed the skegs behind the rear wheels, for instance. I'm not sure what's optimal there, you see some ka-razy stuff on race cars. I'd go for a spat that is 'flat' on the outside and curved divergently on the inner side. Combine the three openings into one. What's ahead of there, gas tank or spare? That's aerodynamically valuable space.
On the front, I understand that air curtains are a convergent duct that shrinks from whatever opening is available to a tall, narrow slot pointed at the face or tread of the center half of the front tire (ignoring the top and bottom quarters). This is not that. There is an example that floats around of an external duct air curtain.
Do you need the driving lights? You could make bullets from recycled dining-room light fixtures.
Active shutters in those three center openings. P-51s had their shutters on the exhaust side, but it's hard to do a walk-around inspection on cars, so for seviceability, shutters on the intake side.