I've put over 2 tons of stuff in my old K3500 with essentially the same setup as the new 2500's, ie 9200 gvwr, 6100 ra and 4600 fa vs current 4800. I had close to the 2 tons available on the ra alone when empty. IIRC about 2200-2400 empty wt.
I've put 3 tons in my dually, grosing at 15K a few times.
Reality is, in anything, it comes down to payload before going over some engineers spec from GM. BUT< depending upon the state you drive in, generally speaking, many do not enforce the manufactures ratings. Wa st is really liberal on this. One would get close to 21K gvw and 10K per axel before being considered over wt. Also assuming you have a paid for wt tag of that amount!
Power wise, the truck should do fine. At some point in time, ie about 12K total, a 9200 gvwr gm does get a bit screwy, in that one will be hitting bump stops on the rear when going over some speed bumps, or if you hit a hole at speed, then start going up quickly, ie a river crossing or equal in a valley....
Marty