Winterize While using:
In the 20-30 degree range should be ok if you maintain heat in the cabin. Most MH's provide some under belly heat.
I wrap the outside hose with quality grade pipe insulation and run a heat tape along the inside of the pipe insulation next to the hose. Then I use some black duct tape (gray will do :-)) every 8" or so. The heat tape (Water Pipe Heating Cable) is avail at Home Depot, Lowes, etc. Cost is: ~$30.00 for an 18 ft. heat tape. It comes on about 35 degrees and shuts off about 45 degees.
Get the better grade pipe foam insulation. I think it's the 1" you'll need and it comes in 6 foot sections. Buy 3 or 4:: have extra
Extra heat tape is good for inside the compartmen.. Don't let the heat tape touch itself since this can cause a "Hot Spot" and melt.
Some people add a heater to the plumbing area compartment, I use a 50 watt light bulb for a little extra heat.
We have been down in the single digits and teens many times and I have not frozen up.
Check underneath for exposed plumbing. Hot water may freeze up, but it's likely the cold going into the hot water tank that froze.
Open inside cabinet doors to plumbing areas if it gets really cold.
You won't need to worry about the sewer hose unless it gets really cold and there is standing liquids in it.
Oh... Use only a high quality water supply hose. Cheap drinking water hoses will eventually blowout and the heat tape could melt it.
I bought a good drinking water hose from Camping World: