Payload is 1600# but it is over that capacity by close to 800# when loaded, the camper is just 1800# dry and when wet and loaded it weighs in at 2300#-2400#. I also tow a 22" fishing deck boat boat that is 4400# towing and hitch weight is 350# and that is set on the 20" extended hitch.
I did add some timbrem's that at normal ride height are touching the bump stop and are just pre-loading about 200#. when I load the truck the air ride self levels and the timbrems help stabilize the load. At highway speed the air ride drops an inch on aero mode and loads about 800# under compression. I had the Timbrem builder help me cut these to length to have the preload and compression load, when the truck hits 62 mph's and the aero mode activates that extra compression and 800# load capacity really stabilizes the load. The truck gets very stable very little sway..
Oh no your payload is not 1600# open up and check your door panel for what your payload is. Or use the online chart. 1600# is Max available for a half ton. Probably less than that actually. And that would be a single cab 2x4 straight truck.
I've never ran Timbrens but I've had that payload in my truck with straight air and it handles it fine. It's that I built my truck for. Though anything more than 3k in the bed I'd have gotten an hd with only the Auto leveling rear bags.
But careful with your tires if you still have factory SR-A's. Even at Max 45psi they don't like that kind of weight. You should really invest in 10plys if you haven't already.