I found this locally at Orscheln Farm supply. Acme # 88304 Class III Step Bumper Hitch (Generic) $49.00, 2” Receiver, Complete w/hardware. Fits the hole spacing in the Nissan bumper perfect.
*3: The maximum towing capacity when using the genuine NISSAN step bumper as a ball mount is 5,000 lb. (2,268 kg) and 500 lb. (227 kg) tongue load.
Standard practice is to reduce that by 10% for every 1” of drop below the original mounting point.
Also found the Factory Style 7-Way and 4-Way Flat Vehicle End Trailer Connector Kit complete with Relays for Nissan here, $44.95