[shilala]

Sorry to hear it, Vin-Bob. That sucks.
You can wrap the hives come winter, insulating them.
Or build a break with hay bales, or do a lot of other stuff.

Think about the size of the hive vs. the size of the colony (which I think you already have a good grasp on).
There's gotta be enough bees to keep the heat up in the hive. If the little buggers are already chilled, they'll bite the dust on cleaning trips even though they'll shorten them.
Consider maybe even a styrofoam cover you can cob out of blue construction foam and tack on, or remove a section?