I put my MTB pedals on my road bike for the winters. My MTB shoes have some room in them. Then I put a pair of thick socks and gore-tex socks over them. I wear them inside my shoes. I am very comfortable in the 20s & 30s. In the teens, it is a little chilly. Low teens I put my neoprene booties on.

You can get the goretex socks for a low price at the sportsmans guide on line store.