I called GM and finally spoke with a live human being who could answer my question, I had to give my VIN # so the correct information could be accessed. I remained on hold for quite a while before he returned with the answer. We were on a recorded line and after being told all of my particular truck weight and payload specifications I asked specifically if the calculation included ALL occupants of the truck (5). The answer was YES. Of course this does not include hitch weight or anything else the owner or dealership may have added after delivery.
I have the date and time as well as the name of the person I spoke with. They also generate a service number for every call for reference. So please, if anyone has definitive information regarding occupant calculations to the contrary directly from GM message me with who you spoke with and when so I can call back with that information. I don't mean to start a rock throwing contest here but if you don't have direct information from GM I have to rely on what I was told.