In the cargo van, at least, there is a clear path for air coming in the bottom of the B pillar. There's an oval hole above the D-ring that opens in the gas filler pipe cavity. Orton first recognized this, and I followed his suggestion of open the oval to round, and will soon use it for my shore line coming into my electrical box. With a good cable gasket, it will become air-tight -- though there may be other, lesser openings around there.I also noticed a lot of cool air draughts on my hands when I was working on my electrics behind the drivers seat. The air seemed to come from the punched holes in the lower B pillar frame.