I just installed the AC fan referenced above per @ValentineWeather's suggestion (thanks for your help by the way). I have it plugged into a WeMo wifi switch, so I can easily turn the fan on/off manually via the Internet .. and automatically via parameters, such as, "fan off IF avg-wind >20 AND time-of-day = night" (but as of now, I plan to leave it on 24/7). You can quickly see the temps rise when it's switched off, even in a 10-15mph breeze. Interestingly, during a rain storm last night, the humidity
increased with the fan on and decreased with it off (for some reason, I thought the fan might decrease humidity by artificially drying the air). So, the fan really does a good job.
This is in a new DFARS enclosure and a with a new SHT31 temp/hum sensor (required -0.9 correction applied to all consoles). At 24 cfm, it's relatively quiet. You start to hear it from maybe five or six feet away.
I read elsewhere on this forum that the corners of the fan would need to be slightly shaved in order for it to fit into the fan chamber. I used a hand-held file on each corner of the aluminum frame:
Installed in DFARS with a tight fit:
Final installation: