We have camped in cold weather (down in the range of 25 degrees back in Feb), and I dont think I would trust the heated hose to prevent the filter from freezing. We didnt use a heated hose, we used one of those long wires that you use to prevent pipes from freezing, and wrapped the hose and the heater in the foam pipe tubing, taped it up with duct tape, and then wrapped it with some fiberglass pipe insulation wrap.
I say all that to say this. We wrapped the heating element around the camco filter, and then wrapped the insulation wrap around it before wrapping the hose. So my suggestion, if you are able, would be to wrap the hose and the filter with some type of insulation wrap and maybe you will get enough heat transfer into the water inside the filter to prevent freezing. We considered buying the heated hose like you have, but decided to continue using the home made method, for exactly the concern you have. Being able to wrap the hose and the filter with the heating element was our preference (we also dont have an on board filter).
But with you having the filter "inside the basement" area, you could possibly put a small heat source (a lamp, small heater, etc, if it will fit) inside the compartment and that should keep it from freezing
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