Something that helps with your water rations freezing... Rather than keeping the water in the trunk, you can keep a supply in the passenger compartment. It will still freeze, but, once you start driving and have the heater going, it will thaw again. Something flexible that can either go under the seat, or hang near a heat vent on the passenger side like a flexible Platypus water container works well, and it can be placed out of the way. They make them in all different sizes, and I've had them go through many freeze/thaw cycles with no problems.