Ed A. Stevens said:
I made and installed rocker protection that does not lose any ground clearance, and it does not even attach to the unitframe (just the pinch weld seam below and the old rocker panel below the door, near the same places the box tube fix gets welded). There are no cross tubes between the frame and pinch weld seam. These guards have been hi-jacked (the static test) and dropped on with the full weight of the XJ (the dynamic test), and they have been used to pivot around rocks (they stick out 1.5 inches past the door sill). The beauty is they complement the lines of the XJ, so few notice they are there. The drawback is they attach at the rocker panel under the doorsill, and if your old rocker panels are crushed it's hard to hide the scars and get a good solid attachment (although they can be welded).