As far as I know (and I could be wrong), the tanks themselves are not heated. The basement compartment is heated and is supposed to keep everything from freezing. However, I'm not convinced that it would work in extreme cold conditions like -0?.
I would be most concerned about the area where the water pump is located. On my Friendship, it is mounted close to the compartment door. I would assume the air toward the center of the basement would be warmer than 2" from the door and outside air.
One thing you must be careful with, if you have one, is the ice maker. The water line and pump for it is in the cover behind the fridge and not in a basement compartment. This area is not heated. I had the ice maker water pump freeze, causing it to split.
Also, driving in cold temps, as opposed to being stationary, would have no effect. Wind chill is only a
"feels like" scale applicable to human, and some animal skin. Air temp is the thing you have to watch. Having an outside thermometer that can be read from the cockpit can be very helpful, including knowing when the road surface may be freezing. If it is 33? and the wind chill is 25?, water will not freeze. Regardless of what it
"feels like", 33? is still above freezing.
My best advice...If you live where it gets cold in the winter...drive to someplace warm