All you need for the super spring install is a couple c-clamps, the stable loads looks even easier, but I think they are for someone who wants unloaded to remain the same and just more support with a slide in camper or bed full of bricks.
I hated the ride with air bags on my f150 and went with supersprings and was happy. I would not go with an add a leaf as I believe that would be to stiff, and not adjustable. The superspring shackle has a couple different bolt height optinons to add more tention if needed.

Do you have the factory overloads that are on top of the spring pack?
I would also change your shocks to bilstiens or rancho rs9000's if you do anything to stiffen up the rear.