Frozen water line from fresh water tank

[RodG]

I have a 2006 Montana 3500RL that has the winter package. I recently returned from a trip to find out that the line from the fresh water tank to the water pump had frozen. Once it warmed up, the pump worked fine.) This unit has the winter package and enclosed belly. The temp dropped to 20 degrees, but the furnace was running at 70 degrees.
Does anyone know of a simple way to add extra heat to the basement?
Wrapping the water line doesn't seem feasible as you would have to drop half of the underbelly to get to them.
I was wondering if you could take up a register and just cut a 2 inch hole in it to divert more of the hot air into the basement. Or is there some after market heating element that you could attach to the basement to add extra heat?
Thanks for any help.
Rod

[travelin texans]

That covered underbelly with a layer of reflex, foil bubble sheet, above it is pretty much the extent of your "winter package". Those terms "winter package", "polar", "artic", sound impressive but do not think that it means you won't have freezing in extremely cold weather.
Now back to your question.
There should be a 2" duct behind your basement wall blowing into the underbelly when the furnace is running. If running auxillary heaters they will not do anything to help with anything below the floor, you must run the gas furnace.