Plumbing Freezing

Prevention

https://www.hunker.com/13417513/how-to-prevent-water-pipes-in-a-mobile-home-from-freezing

https://redrivermutual.com/safety-guides/preventing-frozen-pipes-under-mobile-homes/

https://www.mobilehomesell.com/winterize-pipes/

Under a Pier Foundation

• Insulate with a skirt, which is tricky to do. [1]
• 3" trench, ground contact treated base, rigid insulation over that, good tape seals, and protect rigid foam with pressure-treated plywood. [2]