The cluster is 95F, it won't freeze.
You'll get more than one response because there is more than one workable solution for the situation.Thanks all. Not too bad a ratio. 6 responses and not 7 answers. Still, I have ~do nothing -> bring them inside. Hmm...decisions, decisions....
All boxes are the same. 10 frame deep with sufficient stores each for a short cold snap and an empty super on top to make space for the feed bag. I have a number of other hives that have more bees, but none with full brood boxes. All have sufficient stores; some have fontant rather than syrup. Most have twice as many bees as the ones I mentioned already, and all have brood. All are rescues from cutouts that I'm trying to get established.
FYI, if the quilt gets wet and frozen into a block of ice over a hive it runs the risk of suffocating them, sounds like it worked for you but more a future warning.The two strongest hives I left out fared well. One had a quilt over it and the other did not. The other was the only one with more than one box. It had brood in two supers, probably 6 frames of brood total, and a brood box above that. The only reason for that configuration is that they decided long ago to draw brood in the supers and not the brood box on bottom, and I only recently gave up and just put the brood box on top.