This is why I think it would be best to switch over to the bigger map soon. If you add in other civs and then switch over later, you have to balance those civs twice. If you switch over now and then add in the other civs, you only have to balance them once. But even if you opt not to use the 96x145 map, I don't think Bohemia and Serbia are too small. They're just as big as the Netherlands, Genoa, and Sicily in RFCE, or Babylon and Korea in DoC.