[livewire516]

Yeah, managing the climate of a living space is much more than just air temp.

I once lived on the top story of a flat-top roof building. My stand-alone A/C was oversized for the room and would run full blast but it didn't matter: The thermal mass of the 'tar beach' above me radiated through the ceiling and practically baked me throughout the night! I was so tempted to sneak a hose/sprinkler up there...

Intuition says I get more utility from secure passive ventilation than the aero penalty from driving since most time spent in the van will be when parked. But as I mentioned earlier, I might look into several smaller vents that protrude less at a later stage.