Another approach could be a half leaf in the forward spring section. Make it a reasonable stout piece, like a cut down main or first leaf. Mount it on top of the main leaf and make sure to add a clamp near the front tip. This provides two benefits, additional wrap resistance under acceleration and reduced tramp under deceleration. The clamped front reduces wrap, the top location reduces tramp. The unaltered rear spring sections allows spring rate to remain intact.

Other methods could be a torque arm arrangement. There are no off the shelf offerings, so this would require some fab work, but could almost be a bolt in depending on design.