Magnets sound like a great idea if you can find them strong enough and assuming that they will actually work on the bows. I'll certainly look into it.
Thanks for the info above Loshde.
My concern with magnets, if sticking to the tent bow, is how to stop the fan rotating on the box. IE, turn fan on, fan acts like outboard motor and stays stuck to the bow, but rotates away.
I may be overthinking it though. I'd love to hear from Russ as to how well his solution works - it'd be perfect if it did work.
As for the magnets, Rare-Earth magnets (grab some from ebay) should be more than strong enough. If you're handy, pull apart a couple of old computer hard disks and pilfer the magnets from inside them. Check out the LED lighting thread somewhere - a lot of clever folk use rare-earth magnets to stick their lights to their poles with the canvas in between. The fans will be heavier, but nothing more magnets wouldn't fix
.
Cheers!
Matto