Congrats.
There are commercially available examples to examine for attachments and such. Aerocaps reduce interior space. Do need that or not?
A high-top with a cubby hole over the cab could be aero.
A soft top might be made retractable.
The ultimate aero would be a bubble top with an integral wing like the VW Golf GTI W12-650:
Plus which, it could double as a roof rack.