It starts with her feet, and once those are warm it'll be something else. Look into full body coverage with Gerbing gear, google it. It's designed for motorcyclists, but it will plug directly into your 12v snomo power. My wife has a disease which basically gives her low body temp and no circulation in hands and feet. She could not ride below 20° until we spent the ~$750 for the Gerbing stuff, socks, gloves, jacket and pants. They also offer rechargeable batteries to use when not on sled. Wasted lots of money on everything else before buying this.