I should have made it clear, the ventilation is primarily going to be used when the vehicle is not moving/running. The 12v fan will be hooked up to a 'house battery' (not the car's battery; likely AGM).
In retrospect, perhaps I should have hunted around for several lower-profile vents, rather that this single large one - when considering aero. I know Sortimo and other van outfitters make them.
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