Browse craft at Dutch brokerages.
Steel / alloy
boats from there are often insulated, at the
boatyards, by/for the owners. Also anything already made fit for the Arctic will have very decent
insulation in the living area (warm area = the main, and the crew cabin/-s).
cheers
(e.g.
https://www.botenbank.com/es/bote/19...ns-54-8851528/) used Simocell foam, etc. typical in quality Dutch metal boats