It's been about a month so here's an update.
I realized I couldn't generate AI for the size of the area I wanted to make. I was also grappling with scale of the map - too small and the buildings would look weird, too big and it would take forever to get around. So long story short, I decided to work on the area of Solstheim until I could figure out how things should work on the mainland. It's still mammoth but at least AI works without carving it up.
Here's an overview. Don't worry, it's supposed to be rough.
The interiors are mostly complete:
Right now I'm looking for snowy rocks and trees for the instance painter.
Any kind of release is a ways off I think. But if anyone is interested in helping with the project, I'd be open to it.