I'm full timing in a TT, but where the winters are much milder than you'll face. I could have just filled the fresh water tank when empty, disconnect the hose and turn off the water. However, I decided I liked the convenience of having city water. I used a good quality heat cable and wrapped with foam pipe insulation. I used 1 inch foam pipe insulation on a half inch line so it would fully enclose both the pipe and the heat cable. I wrapped the heat cable around the facet and facet pipe and insulated with insulated wrap. Also did the same to the trailer inlet connection.
For skirting I suggest insulation board that can be purchased from most hardware stores. You'll need to cut it to cover the wheel wells. Be sure to tape the seams and leave a way to access the gray and black tank release valves.
Because of the severity of winters in your area, I agree with Roy M that you need to put a space heater under the trailer with the thermostat set at about 45 degrees or higher. You should be able to operate 2 space heaters at medium setting with a 30 amp trailer. However, if you try to use the micro wave with a heater on, you'll trip the breaker.
Here are the links to what I used:
https://smile.amazon.com/gp/product/B07331JKPR/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&th=1
https://smile.amazon.com/M-D-Building-Products-50164-Self-Sealing/dp/B001HQTZ7A/ref=sr_1_6?crid=2Y3IQIZBO7PCA&keywords=split+pipe+insulation&qid=1577928786&sprefix=split+pipe+%2Caps%2C134&sr=8-6
https://smile.amazon.com/M-D-Building-Products-50164-Self-Sealing/dp/B001HQTZ7A/ref=sr_1_6?crid=2Y3IQIZBO7PCA&keywords=split+pipe+insulation&qid=1577928786&sprefix=split+pipe+%2Caps%2C134&sr=8-6