I was able to find specs from Toyota about my truck GVW = 5350, Curb weight=3855 which leaves 1495 for payload.
Actual payload in your case is what ever the rear axle (RAWR) is rated for as it going to carry all of that TC load. In fact this type setup can and probable will unload the trucks front axle.
Weigh the trucks front and rear axle. A single gross weight (GVWR or GVW) doesn't give you the most important part of the trucks safe loading story which is RAWR = tires/wheels/rear spring pack.
Your 265/75-16 Cooper AT 3 comes in C @ 2470 lbs or E @ 3415 lbs. However without upgrading OEM wheels (if needed) you gained nothing from a safety perspective.
Think first about a safe mod for the trucks rear suspension and wheels....and hope the TC doesn't unload the trucks front axle too much.
