Actually, if we're talking about pre-1230 POD, Doukas would have much more than Epiros - actually, looking at the map there's uncany similarity to 1340 OTL Byzantine borders (includes Epiros, Macedonia, Thesally and southern Thrace). Although, even if Bulgaria stayed friendly to Doukas, the Roman Empire under him would still have problems with Serbs, Nicea, Latin principalities in Greece and most likely whoever rules south Italy - be it Hohenstaufs or Anjou...