All the duchies I know of are spoken for.
If you can carve one out of BoM, it's all yours.
Think about all the benefits of living in the Frozen North:
+ Free life-time supply of slushies and other icy treats!
+ Skiing! Snowboarding! Yeti wrestling!
+ The Vikings are drunk, pliable, and complacent. There would be no pesky nobles plotting your downfall from within your own realm.
And that's not all!You get life-time immunity from CE! Seriously. It's too far away and too cold. The last time Enri marched up there half of his
laser bears troops froze to death.