I think the main reason for this is that the instructions specifically call for a 6-1/4" hole, and the only hole saws I could find in that size were for wood only. The 6" worked fine but it only had about 1/8" clearance on the diameter. A friend of mine used a plastic spacer for his roof fan and it cracked pretty quickly so I didn't bother with that. I've been living in the van for about 6 months now and I have yet to encounter any issues with this fan install. Fingers crossed about that, though.

It’s definitely strong enough for the space, but if you’re expecting much of a noticeable breeze you’ll be disappointed. It mostly just does the job of regulating temperature/humidity. One of the great features of this van is all the ways you can open doors and windows for crossbreezes, so the only time I’m ever relying on just the fan and a cracked window for ventilation is when stealth camping. For that purpose I recommend pairing this with a pair of window rainguards.

It moves enough to equalize the temperature. You can’t really contrive much of a crossbreeze out of it. I wouldn’t use it alone in a space bigger than this. Also be aware that it is exhaust-only and the impeller-style blades don’t do anything when reversed.