Drain the ballast and forget it
The ballast should be drained whenever the boat is out of the water anyway. With no water in it, I can't see why you would put in antifreeze. I leave my drains open for evaporation. No problem with mice, too high up, but small birds could fly in, I suppose.Also, if the furled jib is left up, it is a good idea to secure it from blowing in the wind with a bungee cord. This keeps the headstay from fraying, which can be a hidden disaster if you don't inspect it when you next sail.Otherwise, just be sure the tarp drains fully and if a lot of snow builds up, take a broom and shove it off from time to time.For the motor, the most important thing is to make sure ALL of the water is out of it. Usually, turning the motor over a few times once the motor is out of the water is enough. You don't want internal water to freeze. I like to run the motor until it runs out of gas after I pull it out of the water and disconnect the gas line at the motor. That way you get rid of the gas and water all at once. All should be OK next Spring when you want to sail.