They say that if you are actually using the RV in the winter, you should make sure the area around the furnace is not obstructed. The warm air should be able to flow easily around to keep the pipes warm.
I also read in a manual that you should keep the bathroom door open and the cabinets so that the warm can get inside keeping the pipes warm.
And if you are using a generator that is water cooled, you should make sure to use the right temperature antifreeze.