I know we had a discussion about this before. Can't recall if anyone posted this link, but this is a shop that sells heat vests. Not cheap though.
https://www.heatedwetsuits.com/?utm_source=windsportatlanta.com
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What happens in a black hole stays in a black hole.
Florida
Heated, body temp "water"
Truckers have been doing it for years. Some tubing and a rubber bottle for the DYIers or buy online: https://www.amazon.com/ONEDONE-Portable-Bottle-Hospital-Camping/dp/B06VWLSV52/ Click on this link and I earn affiliate credits on Amazon.
Or, Florida like Langdon said.
--- The Arrogant Jerk: Crabby and irritable since 1998.
Florida is working for my shorty and sometimes a full wetsuit