Neil,
Are you going to use "conventional" side mirrors, or do you plan on video cameras?
It's not soon in the process design process to be considering something like what Nissan did with the LEAF; an up-stream air-splitter for the morrors. In Nissan's case they say the very strange, sticks-up-above-the-hood/body-panels turn-signal/running lights contribute significantly to reduced wind noise from the side mirrors, if not actual turbulence reduction.
Lest I forget, you're doing an excellent job keeping us informed about your fascinating project. Thank you and keep up the good work. (Are you getting much sleep?
)