I've got some crazy thick high bulk brushed acrylic socks that I wear OVER my summer shoes for when it gets cold. The inside of the sock almost looks like cotton candy, and they are very stretchy. I went with the largest size they had and cut holes for the cleat area and at the heal to turn them into pull over shoe covers. Sometimes I wear my nylon shoe covers over them. They are T-Max Heat which is a brand of a Canadian chain called Marks, no idea who in the US would carry something similar.