Vizard discusses offset rocker bushings in the "Mini" book, but for the length between stands (4"?), with the 1st and last rockers only supported on one side, I'd rather see a bigger stand and bigger shaft. If the shaft wall now is (just to make the math easy, there are several thicknesses) 3/16", going up to a standard auto size of 7/8" at the same wall is a 44% increase in bending resistance.
Reducing the size to accommodate a bushing with enough wall thickness to allow useful eccentricity doesn't look easy. If .020" is the minimum on the thin side, even dropping to .500" shaft only moves the fulcrum .121".
