Buy a bunch of these adhesive warmers and stick them onto you all over your body:
HotHands Insole Foot Warmers With Adhesive - Long Lasting Safe Natural Odorless Air Activated Warmers - Up to 9 Hours of Heat https://www.amazon.com/dp/B004PH33NU/ref=cm_sw_r_apan_glt_fabc_C2RWWGZPVJVZTNA70EKB?_encoding=UTF8&psc=1
They are sold as foot warmers, but they're the only ones I've found that are adhesive.
Be sure to leave a layer or two of clothing in between the warmer and your skin, or they could hurt you!
Listen, I know they aren't the prettiest things(not that you can see them), but these in your shoes before you go will help you stay warm. We hand them out to homeless youth during the winter and people say they are very nice.
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