Sound Insulation
Once the rust situation was stabilized, I added a layer of sound insulation (the silvery stuff) to the package shelf. The opposite side of the shelf and vertical surface were covered as well. The material is similar to the stuff called "Dynamat," but a good notch less expensive. It's surprisingly easy to work with. The adhesive backing is just sticky enough to hold well, but not so sticky that it creates difficulties in installing it.