we have an old 3 bulb projector used with a 9x12 screen about 8-10 feet in front of it.
we put the sensor strip on the PROJECTOR and the bowler about 8-10 feet behind the projector. it worked fine. it was placed directly behind the Wii (which was placed on top of the projector - which stands about 16 inches high). you don't really see the projector as you concentrate on the screen.