If you ditch the tube, use an insulating jacket for your bottle, and start with warm or even hot water, you shouldn't have too many freezing problems. This Seattle-area forum
has some interesting ideas, not all of them feasible, but some amusing. Freezing bottles have been a problem here, where temps have been below freezing, often down in the teens, for weeks.
Edited by OregonMouse (01/17/17 09:51 PM)
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey