We are all here for different reasons and we all place a different value on a comfortable car. I see your point about the low miles making a pay back lengthily.
A grill block is a good place to start, the block heater is a nice one too
You might look into a little electric heater (space heater) that can run off the same timer as the block heater. That will keep you warm, frost free interior windows, and still get good MPG.