What is the proper way to bring a water line in through skirting on concrete runners?
As for the best way to solve this properly, I'd say "put the house on a foundation" but that's clearly not what you are looking for. 

Digging the trench to the point(s) where the water and sewer connect and then building an insulated box with a hard skin to keep animals out of it (cementboard or metal) to contain the pipes running vertically. Otherwise you're into the godawful failure-prone land of wrapping things in heat tape and insulation, and hoping you don't have a heat tape falure that either freezes your pipes or sets things on fire...