It's doable, depending on how much payload is taken up by passengers and cargo.
You have somewhere around 1230 lbs of payload. That's room you have for weight from the trailer tongue, WD hitch, fuel, driver, passengers, and cargo, in or on the Suburban. If 6000# is loaded trailer weight, the hitch and tongue weight will eat up about 800#.
A while back, we had a poster asking pretty much the same question. Turned out, he had six kids. His driver / passenger / cargo weight was close to 1000#. A full tank of gas and the WD hitch, put him at his max payload. Any tongue weight, would put him over.