The hydration bladder approach just doesn't work, and I'd agree problems start to occur below 25F. The tube is the weak link. An insulated tube cover barely helps.
I've used insulated wide mouth nalgene bottles inside my pack with clothing layers around when snowshoeing because that's what I had on hand, and kept a platy bottle against my chest. However, now I'm looking to pick up wide mouth nalgene brand soft canteens.
