If I could make one suggestion,
Please give each province an actual X,Y coordinate and then a way to get actual distance between provinces.
The reason I suggest this is because "distant vassals" in CKDV is a kludged add-on system which sometimes worked, but sometimes resulted in strangeness. F.ex. the King of Hungary was nearly unable to hold on to the Duke of Venice (mere inches from Hungary) but perfectly able to hold on to Byzantium because both were "Eastern Europe" while Venice was "Italy".
Please give each province an actual X,Y coordinate and then a way to get actual distance between provinces.
The reason I suggest this is because "distant vassals" in CKDV is a kludged add-on system which sometimes worked, but sometimes resulted in strangeness. F.ex. the King of Hungary was nearly unable to hold on to the Duke of Venice (mere inches from Hungary) but perfectly able to hold on to Byzantium because both were "Eastern Europe" while Venice was "Italy".