OK, my Fantastic Endless Breeze 12 volt fan arrived today, so I had to take it out to the TT and check it out. At the highest of 3 settings, it draws 2.6 amps, and makes a nice little breeze. It does appear to move the 900 cubic feet of air per minute claimed, which will be enough to completely change the air in our 21 foot TT about every minute and a half. The noise wasn't bad at all. Certainly a lot less than the fan on our furnace or the AC unit.
At 2.6 amps, it will take about 20 hours draw the house battery down to 50% or thereabouts. I'm guessing that 15-20 minutes at full speed to cool the interior, then the rest of the night at low speed might just do the trick.
I believe we'll have to test it out in the driveway tomorrow night.