I have included a few links which, with 20 years sailing experience may be of only passing interest to you. But there are still some good recommendations included..especially from Morgan's Cloud.
The numbers of boats to have successfully sailed in Antarctic and sub Antarctic conditions is varied. A good strong offshore design, built of your choice of material, well insulated, centre cockpit, over rigged with lots and lots of ground tackle and a huge drum winch is a good starting point. Then it's all down to comfort and redundancy in systems.
I have never seriously considered the type of voyaging you are planning. I don't mind being cold, and I don't mind being wet; but being both at the same time (for an avowed tropical voyager) is definitely a no-no for me. But, I have a friend who ventured into the Arctic occasionally and he and his wife sail a Skookum 53 motor sailer. Built like a tank, roomy and comfortable, it has served them well for 18 years.
I hope the following is of some service. If you have trouble viewing any on the links, especially Morgan's Cloud, copy the link into your search field and it won't prompt you to login when you try to open it.
Impact Resistance of Sailboat Hull Materials
Mahina Expedition - Selecting A Boat for Offshore Cruising
(Everyone considering the purchase of a sailing boat should read this thoroughly)
Adams 40 “Glenshiel VII” | Sail monohulls | Boat Sales Tasmania
Recommendations For Sailing The High Latitudes In A Fibreglass Boat
(Some really good comments follow the main article in the above link)
Time on Ice: A Winter Voyage to Antarctica: Deborah Shapiro, Rolf Bjelke: 9780070063990: Amazon.com: Books
Aluminum Expedition Sailboat Morgan’s Cloud
53' SKOOKUM KETCH/CUTTER BLUE WATER CRUISING YACHT
Used Allen Payne Skookum for Sale | Yachts For Sale | Yachthub
This is not a Skookum, but a recreation of an Allen Payne classic. This to me would be almost perfect....
1978 Skookum Pilothouse Motorsailor Schooner Rigged Schooner Sail Boat For Sale -