Looking forward to your testing !
Since it has a removable hardtop, you have the opportunity to create a nice top that you can replace when you want.
Since the car is rear engine, I would guess that some ventilation would be needed in the design.
With the airflow being pulled onto the back of the car, this might even help the airflow stay attached, and that is a real plus in your efforts.
Did I miss the year if your car ? I didn't see it.
Looking at the photo though, I'm guessing this may be the design of your car.
You may find this hardtop Miata interesting.
You could do something similar. ( And it actually would look cool too ! )
Click the video link :
https://youtu.be/ymvI_h1VwgI