>Does anyone know the maximum time bees can stay cooped up without defecating inside the hive? I have never seen any info on this.

I've seen one winter here where they didn't get to fly from late September to mid April. That's six and a half months. There was a lot of dysentery and higher than normal losses, but not that bad of losses. Most winters here winter doesn't really set in until October and they get a potty break about once a month through the winter.