In our previous unit, which did not have tank area heating, we used colored light bulbs for the tanks and behind the refrigerator (to keep the ice maker line from freezing).
We never had any problem down into the teens at Lake Tahoe.
We also kept the cabinet doors open inside the unit
Sealevel Ram, 2004 Ultimate Freedom
"If the women don't find you handsome, they should at least find you handy." Red Green