The bar is hidden and is used to support the headliner by three "screw/washer gizmos" as you deduced. I originally went the cardboard route and made a perfect mess of the cardboard and myself with the water and ammonia. The end result was horrible. I never thought of the bowing ball idea although my fist and temper came into frequent play.
After getting some input here on the 'Bolt I ordered an ABS one. It went in fairly easily and looks great. The ABS may fail the purity test but is sure looks good.
Don
