When I was a wee lad, my dad was stationed at Loring AFB in northern Maine. We lived in a 38-foot (uninsulated) mobile home seventeen miles from the base because there wasn't enough base housing available. Some of my earliest memories are of frost— frozen condensation— on the inside of the walls all
winter; wearing sweaters and coats indoors, and even heavier coats outdoors; getting bathwater by melting snow on the stove because there was no plumbing that wasn't frozen; and "helping" pile snow against the walls of the mobile home to turn it into an igloo— not that I was a lot of help at that age, but building a snow tunnel to our door was fun. And it never got down to -30°F, more like 0°F.
We eventually insulated the mobile home, if you can call it that, by drilling holes near the ceiling and filling the walls with sawdust. Back in the early sixties, that was state of the art in mobile home insulation.
I can understand the appeal of briefly camping in sub-freezing
temperatures so you can play in the snow, but sub-zero
? Not a chance! Unless you like living in a refrigerator, because your furnace, running 24/7, probably can't keep the inside temperature much above freezing. On the other hand, you'l have more propane for your furnace because you won't need to run your fridge!
A wood stove will help, but stoves put more of their heat out the chimney than into the trailer.
So, having done my duty by trying to dissuade you, here are some potentially helpful suggestions since you'll probably go ahead anyway…
Park where you've got lots
of sun exposure. Especially morning sun.
Coat the trailer with something dark that you can remove later, so that it will absorb more heat than it reflects.
Make sure you've got a windbreak in the direction of prevailing winter winds.
Put a skirt around the base of the trailer to keep wind from blowing under it.
Use a heated freshwater line. Assuming, of course, the municipal service you're hooking up to isn't frozen. If it is, then even a heated hose won't help, and you'll be left with using bottled water bought at a store and carried back to the trailer inside the cab of your tow vehicle where it won't freeze en route
Don't even think
of using an awning. In fact, remove the awning and store it somewhere safe and warm.
No matter how cold it gets, leave at least one window cracked open for ventilation so you don't asphyxiate yourself with your wood stove.
Add the highest R-value insulation you can get, regardless of cost. Two layers of 10mm Prodex at a minimum. Don't forget to make insulated covers for your windows, too.
Don't use your holding tanks. At all. Even if they don't freeze, where will you dump them? The dump station will be frozen, and they won't have running water to rinse the hose. But if you do
have a place to dump the tanks, store your slinky inside so the plastic doesn't crack from the cold.
Sub-zero camping will be a whole lot like living in a cave. Except you'd have fewer problems living in a cave.