Ventilation is for two reasons, ammonia and humidity. If you get rid of those through alternate means, you can shut the door.
A 5-gallon nipple bucket is in our coop, but if he won't heat, there are electric nipple waterers, so there is no open water.
We use horse bedding pellets which...
I'm in Wisconsin so nearly the same thing. We do heat our coop to 40F for two reasons...
(1) So homey doesn't have to haul water through snow drifts in the wintertime because their water froze.
(2) No frozen eggs, chickens, wattles, etc.
We use a thin, oil-filled, radiant heater we've had...
Can use a face mask. They put the ear loops over the wings.
I've also heard some people make them, so could check eBay or Facebook poultry groups in your area.