The unit I had in my reply above had two grey and one black tank all exposed. When I bought the trailer as part of the deal I had a heat blanket under all three tanks and then encapsulated each tank with foam. Plus mobilehome skirting kept the cold wind out underside.
The down side for me of not using the city water hookup is hearing the pump run plus trying to refill in 45 mph winds at 0 to 13 degrees a couple of times a week wasn't worth the hassle.
I found it was much simpler for the 4-5 months of winter for me was too make my own heated water hose and and a permenant drain line forget about it.
No messing with water hose or a drain hose 4-5 moths of winter....couldn't get any simpler than that.
