Hi Ben; Welcome to Permies!
My opinion is not worth a lot here, but I think it might freeze and break... I could be 100% wrong though.
Only experience I have with anything like that is from a childhood of using an out house. Pile got very tall in winter, lucky it was a 2 holer... We sprinkled lime on top each time but not till spring did the level drop.
None of that helps you a bit...
Only someone who has done exactly what you are attempting could give you a proper
answer.
Good luck with your plan , I hope someone more knowledgeable will respond.