You and Mr. Wellie have it well planned out
My one suggestion would be instead of the fireplace get a fireplace insert. You can leave the doors open when you just want ambiance. Then the doors can be closed and work like a wood stove. Wood stove inserts put out more BTU's and will not steal heat from the room as a fireplace does.
It's also good to know how much wood you will need for a 4-6 month period so it can be stacked, dried and ready to burn. There is nothing that sucks more then trying to cut wood, even previously downed trees, when it is single digits outside.
At the cabin we only have the one heat source as outlined in an earlier post - A jotul Oslo wood stove plus a milk barn electric heater in the bath room. We also have a 5 foot wide ceiling fan hanging from the ceiling in the great room (Living, dining, kitchen). This really does a great job of keeping the heat circulating around the cabin and not roasting out the second floor.
Currently when it gets in single digits we close off one of the bedrooms on the first floor(Bunk room) plus the bedroom and bathroom in the loft/upstairs. So all in all, we would be good with the exception of the fan as we need electric for that. We do have a moderate solar system and have ran our fan off of it using a converter in the past. So in theory that wouldn't be an issue either as log as we gotz da' sun.
With all of that said, soon as the winter is over, I am going to keep an eye out for a kerosene heater on sale from one of the big box home improvement stores. I would not purposely use a kerosene heater as fuel will be tough to come by but in a SHTF situation...One is none and two is one. I have used one in the past and they burn relatively fume free. They hold about 1 1/2 gallons of kerosene which lasts about 12 hours or so. So in theory you would burn 3 gallons a day or 90 gallons a month if need be. Rather costly but heck I would rather have it and not need it then need it and not have it.
Last, like you Wellie, our cabin is situated so in the winter we make good use of the sun in our great room via the windows that face south.
Thanks again Wellie for sharing your situation and plan.
Mr/Mrs home owner with only electric powering your boiler or base boards...What is your plan?