Here's a thought. Use the AeroSport controller to cut off flow to the overhead from the NACA's in back. Force air from the ice cooler through its own opening into the overhead and let the chilled air come out the overhead vents. At altitude, open the NACA controller and let cool ambient air in. No biggie if some outside cool air back-flows through the ice cooler, right? Still ends up in the cabin.
No better time than right now to plumb this into mine while I build. I think the rearmost removable panel could host this secondary air inlet with ease. Would probably help a tiny amount to insulate the portion of the cabin top that's within the overhead. Also tinted windows and a non-black interior...