Rosetree, I would set up normally the way you intended for the main room and unless you are being paid for additional coverage to the other rooms...as a courtesy, I would run a powered monitor (mono) in each of the other rooms..control the sound system with a mixer..Do a sound check with a recording playing..I would also keep the monitors on the floor, just inside the doorways you described..

On the floor will give you the best fulness, and away from the crowd..decent coverge..

If you use wedge monitors..try turning them towards the wall and 3-4 feet from the wall..