I live in FL now but I can help you. I am a 20 year VW mechanic who (did) work outdoors in Ohio many times. I figured out to go to Home Depot and buy 2 sided mylar bubble wrap reflective insulation for water heaters ,windows, etc . It comes in a roll and looks like aluminum foil on both sides. Use a sharpie marker and mark around your foot (minimum ) and up the top of your toes if you have room in the boots .Cut out boot soles for you're feet . Put duct tape on the big toe area and the heel area , both sides to prevent it wearing out the bubble wrap mylar too fast. These insoles reflect the heat from your feet and will help keep you're feet from getting too cold. It wears out over time but it takes a lot of walking to wear these soles out. This can keep you detecting for a long time in the cold.