I also hunt in Michigan winters. If I can leave the gun in a cold, safe place where no condensation will form, then I just pull the primer. If the gun has to come inside to warm tempratures (house, cabin, etc...) then I will remove the breech plug, pull the load and clean / wipe down the gun.

One area I due have to drive a ways to the hunting spot. I will clean and dry the gun the previous night inside. Then reload the gun (minus the primer) and leave it in the case in the house. Gun leaves with me in the morning.

I learned this the hard way a couple years ago when I took at aim a late season doe. It was very cold and I had brought the gun in with me after the morning hunt. Never hunted ML before, so it did not cross my mind. Heard a "click" and had fireworks come out of the end of my barrel. It only takes a couple minutes to complete a reload, so I would rather have the confidence of knowing the gun will preform.