Why dont you use a map from the end year of the Game as a reference? Only include those county's .Thank you for that, I will try to update it to something better.
I will probably compromise and go with the 1250 version, but well see. The 800 version seems so drastically different and none of the maps I have seen depict it like that.
Off Topic **CK3 Engine Idea LOL
Create your own counties based on population , you split a region to counties based on population . Literally changing the political map during your game !