Nothin like some cows to warm things up!
Tall coop will help keep the ammonia up high, I assume you have some venting up there?
Humidity might be your worst problem...might think about a heated horizontal nipple waterer to keep evaporated water limited.
Just curious, what is your climate and how long have you had how many chickens in this setup?
Oh, I hope you update this thread with pics and how you made it thru winter.