Rides much better and with NO harsh ride due to the pivoting shackle design.
With that pivoting shackle arrangement, those ladder bars are doing next to nothing for you. The purpose of the ladder bars is to keep the rear axle in a "controlled arc." With shackles at the forward ends like shown in the photos, there is no such control imparted upon the rear axle ... the shackles allow the ladder bars to move fore and aft.
My suggestion is to mount the forward ends of the bars directly to those end-plates, then weld another (smaller) drilled plate to the cross-tube. Doing that will place that forward-most bolt in a double-shear condition (MUCH stronger than single-shear). [EDIT - Oops! I went & looked at the pix again. They're already set up for a double-shear bolting arrangement. So all you really need to do is ditch those shackle plates.]
What I did like seeing was that the manufacturer positioned that forward mounting point below the frame rail. I've seen a few ladder bars bolted directly to the frame rails without even a sandwich plate to spread the load ... and they subsequently pulled holes through the frame rails.