I really dig your idea,as I plan to create 'microcosm' mods for personal use, but have one suggestion,... if you don't think the image would be too redundant,...
Have you concidered altering the mines at all? Since fortresses and (esp.)
barricades hardly ever show up, and collonies and barberian camps disappear
eventually, it'd be nice to have an altered, culturally specific, perhaps, statue
or something else small near or by a mine.
I dunno,... your call. Just though I'd bring it up. Maybe culturally specific
roads would be better for this though, since there would be more variation.