Newer half ton trucks are made to be comfy vs being a load hauler. Do you have the max payload package as well? A lot of half tons (mine included) can benefit from something like airbags, Timbrens, or similar to help with the squat. If you're running a heavy tongue it will also help the bounce on rough roads or expansion strips.
They won't do a thing to help payload rating but they will help firm up the soft suspension.
FYI - my tongue weight is around 825# and I'm running the 1000# bars on my Blue Ox. Love the hitch and the ride of it.