The op has not posted since his initial. I wonder what he ended up doing?
One time, many years ago i hauled 2300 lb of sand in an 1989 chevy k1500 4x4 from a quarry back to my house, about 3 miles or so. I had installed one ton rear springs in it prior.
It handled the load ok, it wasn't on the bump stops with the one ton springs, but it sure wasn't fun. I went very slow the whole way and it still took a lot of brake to slow it down.
I was worried about bending an axle shaft or snapping off lug studs but made it with no damage. That was a one time deal. Made 2 trips, the second was about 1800 lbs if i remember correctly. My brother also hauled some for me in his 1990 2500 series chevy. We got it done, but again, not much fun.