Letting the pile freeze sounds OK to me. Having
enough cover material on hand that you don't have to break through frozen parts will help when adding to the pile. Lots of cover material piled on & around it as insulation, and maybe even growing some supplemental greens to maintain a generally larger pile, can keep things going through some very cold weather. Or you could use different methods through the winter.
One option is to take some sewer pipe, bury it vertically, and build a worm tower that is protected from frost. You may need to adapt the standard design to work better in the cold (less distance above ground vs. below; a very deep, insulated plug; maybe relying on
native earthworms rather than compost worms; mulching very deeply around the pipe) or build it in a hoop house, but this article will give you the basic idea:
worm tower Another would be to use a powdery cover material to pre-compost your material anaerobically indoors, harvesting some liquid and storing up a fair amount of solids over the winter. One commercial system is discussed in this
thread:
Bokashi and Effective Microorganisms Yet another option is to keep animals indoors, or in a sheltered environment. Between them,
rabbits and
chickens can handle a wide variety of scraps.
Chickens and black soldier flies are another combination I've read good things about. Red wiggler worms are also popular, especially when space is limited.
"the qualities of these bacteria, like the heat of the sun, electricity, or the qualities of metals, are part of the storehouse of knowledge of all men. They are manifestations of the laws of nature, free to all men and reserved exclusively to none." SCOTUS, Funk Bros. Seed Co. v. Kale Inoculant Co.
