Every manufacturer's tow ratings have disclaimers not to exceed any other rating either. That means GVWR, GAWR, receiver, and sometimes frontal area. So the tow rating is limited by the lowest of all of them, not the highest. Consult your owners manual as well.
7500 pounds is the tow rating for half tons using a WDH. Otherwise, it's typically lower, 5000-ish pounds or 500-600 pounds of tongue weight.
And I agree that 6500 pounds dry is not going to provide a comfortable experience for the driver or maybe passengers too of a Tahoe.