Charlie,
There is a reason people are recommending a weight distribution hitch and it's not from reading internet posts. They are designed to evenly distribute the weight, so rather than your rear end sagging it spread's the load across both axles so in a perfect world you would see roughly the same amount of drop in the front and the rear.
This would eliminate the people flashing their brights at you. Yes a half-ton has soft springs and heck you could even add a leaf, but that still is just fixing the load over a single axle and not distributing the weight.
Having hauled with and without I can spot the trucks that are not using them as they are going nose high on the highway.