Like almost every vehicle below the 1 ton truck class your Durango is extremely likely to run out of payload capacity long before it runs out of engine. The only way to answer the question is to know how much weight you will be planning to put in the tow vehicle vs the available capacity. Today's trucks and SUVs are treated against an industry standard that accounts for a full load a fluids and a 150 pound driver, but the tow rating does not account for any options beyond the usually base model tested, or things like a family and luggage.
