I just put an electric fan heater in my van 9f it's due to freeze that night, set just above frost setting.
easy peasy. the fan ensures that the warmer air is circulated around the van.
and as for freezing in the hose, this will be my first winter with hot water, so hopefully I won't have that problem any more.
it might even keep the pole warm enough so that the top sections don't freeze up!