You mention you'll have access to shower / bathroom other than your RV, so if you eliminate indoor plumbing from your RV, the only thing you have to protect from freezing is yourself.
There are a lot of videos on google about folks living "off grid" in stationary RV, not sure about alaska. most of them rely on wood stove or waste oil heater, due to very cheap and accessible fuel source (compared to LP and elec).
Have you camped before in sub-zero temperatures? It's quite refreshing when you get up at 5am for a morning whizz and it's well below 0F outside and in the teens inside, and that's just my Michigan experience.
moisture is another issue, you'll constantly be struggling to find a balance between retaining heat and ventilating humidity. I myself give off tons of moisture - some folks get away with cracking a vent and their rv stays dry; I myself can have every window open 1/2" and the roof vent fully open and still have water condensing on the walls. Without running an electric dehumidifier my little rv (20ft trailer) gets clammy very fast.
I'm not being negative about your dream, it sounds very cool and I envy your bravery. I want to share some of the observations I've made camping in Northern Michigan, which is often as cold or colder than many of the more populated areas of Alaska.
2013 KZ Sportsmen Classic 200, 20 ft TT
2020 RAM 1500, 5.7 4x4, 8 speed