Let them out of the coop would be my suggestion. I have never had a feather picker in nearly ten years and many chickens, but I don't close my coop doors during the day, and if there is snow on the ground and they don't want to walk on it, spread a thin layer of straw. Or pine needles, or hay, or mulch...they will walk on that. They will follow a path of straw as if it was a sidewalk. Cold and blustery is a lot more uncomfortable to me than it is to them. Today I am in coastal Virginia and winters are temperate, but I spent 12 years in the upper elevations of West Virginia, with chickens, and they were out every day in every weather. They sure were not bored, and they never even thought about turning on one another.