I never calculated how much fuel wood I use but the last couple winters I have gone around the house insulating and sealing up leaks. Used to need to fire the furnace constantly and never get it really warm. Burnt a lot of wood and coal along with electric and propane heaters for the really cold times.
The insulation, caulking, and spray foam has made a big difference in the amount of fuel needed. Covering windows with plastic or even blankets or heavy curtins can help depending on how good your windows are and how good they are sealed up. I’ve lived places where you could feel the air blowing or just the cold coming right through the glass or especially around them.
Blocking off spaces can make a big difference in the ability to heat but, of course, you need to consider where any pipes and drains are so they don’t freeze.
As far as the heat pump (mini split), maybe building an enclosure (solar heated if possible) around the outside unit would make it more efficient in the heating season.
I haven’t done it (other than at a workshop) but one of the diesel heaters rigged up like a window air conditioner to exhaust outside might be an option.
Short of buying more firewood or other fuel, dressing warm and lots of blankets and heat tape on the pipes?
I have used kerosene heaters before and loved the steady heat (and often the ability to cook or heat water to add humidity) but the fumes can get really bad. Aladdin lamps throw a lot of light as well as heat. They can use a good bit of kerosene (lamp oil) compared to normal kerosene lamps but they seem to burn clean and have WHITE light using a mantle. The heat could be a nice byproduct if you can safely use it. Besides the fire risk, the mantle is fragile and the glass itself can be broken.
Somewhere around here I have a book called “Movable Insulation” by William K. Langdon. That one has a lot of ideas.
Good luck this winter. I’m sure you will figure it out and be more prepared next year.