1. I don't debate that the added gussett adds something
2. I do question why reinforcement is needed in that location

3. I also wonder what other areas have already been reinforced that then requires some added stiffness at this location.

4. Without knowing more then pictured here, IMO this is just chasing your tail modifications

5. In most situations, there is very little vehicle mass this far rearward, the leafs being so far forward biased transmit much smaller forces at this location to the chassis this far rearward, horizontally and vertically.

6. A simple panhard bar would remove much of the original horizontal forces at this location