Hey, Guys up North, I haven't seen anyone mention dry sugar placed on top of the brood yet. Since the OP was concerned with moisture I was under the impression that sugar could actually help with that also.
Well. I calculated how much you need dry sugar to catch the water arising from consumed sugar in the hive.
When hive has 20 kg winter food, it produces 67% water. It is 13 kg or litres water.
How much you need sugar....
Let suppose that sugar takes in 20% water, it starts to leak.
Let's choose 10% water content....so we need 130 kg dry sugar to catch the water
Is it easier if you feed 66% sugar syrup to bees the box full. So it goes in normal way.