We are driving to Florida end of January , question is can we use black water tank or will it freeze and cause damage. Manual states there heat pumped through the basement
We use our (toilet only) while winter travels from Chicago to AZ. and use the pink stuff to flush and all is fine. Last year most of the trip was at -5
Not sure about your specific model, but many RVs have "heated tanks" only when the furnace is running. If it's cold enough to freeze water, you'll likely be running the furnace though.
The gas fired furnace heats the basement compartments on the 35U and I have been fine with mine Fresh/Grey/Black staying in the White Mountains where night time temps dropped to the high 20's. Be sure all the seals are good and the hose port in the wet bay is closed.
Top off the propane before you leave to ensure you don't run out.
__________________
Neil V
2001 Winnebago Adventurer WFG35U