If you wanted historical compostition then it would be better to have 5 Hastati, 5 Principes and Triarii and modify the Triarii unit number to half that of the Hastati and the Principes. Then have 1 Equites,1 each of the Roman reserves and 1 family member. Then the senior Tribunus would gain command of an allied Legion which would consist of no Roman troops but Allies and Mercenaries recruited from Type 4 governments or ones with good Local Support barracks.