My GMC Acadia is rated to tow 5200 lbs, but it never can do that much....
Gross combined weight rating (GCWR) is 10,450 lbs
Gross vehicle weight rating (GVWR) is 6459 lbs
With the Acadia fully loaded (1397 lbs max payload) with family, dog, and tongue weight it would weigh 6459 lbs (hopefully not more LOL)
GCWR 10,450 minus GVWR 6459 lbs equals 3991 lbs maximum trailer weight.
That is based on 5200 lb tow rating with a 6000 lb trailer.
Check out the Audi Q7 Diesel, it might have the tow rating you need.
BTW, my Acadia has a 1397 lb max payload and my Sierra has a 1420 lb max payload, not much difference!