Propane costs too much. Thinking of buying a lot of electric space heaters and just putting them in the rooms we actually use.

We bought a new home about a month ago. It used to be a school house that functioned as a disaster shelter for a small town. The walls are well insulated, but on the second floor the ceilings average 12ft high and at some parts are around 18ft. AND the whole home is around 5,000sqft and 2 floors. In a month we went through around 300 pounds of propane with the thermostats set to 64F. It's going to cost about 700 to fill it back from 30% to 85%. We can't really afford to do that every month (EDIT: I can afford it. I would just some ideas to save money. IF THERE ARE ANY), even if its only during the winter months.

So, I'm thinking of buying some space heaters, like 6 total, and use a like 4 of them to always go to ambiently sort of heat the house and then my wife can take one with her around the house where she's doing whatever and then I have one in my home office warming me up. Then setting the thermostat to like 55 for the whole home.

Some things that are making me hesitant is that the home uses a boiler and radiators. The pipes run along the wall and with the freezing temps outside I don't want to run a risk of freezing those pipes.

Any thoughts? Is my thinking right, or do I just suck it up and pay the cost for propane during the winter months? Anyone else have to deal with something similar?