Early proposals where in fact for a 3 faction game. The Empire had the Warrior, Inquisitor, Agent, and rumored to have the Imperial Guard. The Huttese had the Bounty Hunter, Smuggler, Voss Mystic, and another Voss class, while the Republic had the Consular, Knight, Trooper, and rumored to have an SIS agent. That was very early, and overly ambitious. Lore wise, in this time period, I would see Hutts, Mandolorians, or the Tionese being the best options for a third faction. Hapes and Chiss have very small spheres of control, compared to the republic. IIRC, Hapes is less then 70 planets, while the Chiss are less then 40 in the NJO era.