I have no specs or facts to back any of this up, only real world experience with the 2010 GMC 2500 Duramax, (which is not as stout as your 2012). I tow a 2009 Fuzion FZ393, usually loaded down with a 4 seat rzr and 3-4 dirt bikes. When I rolled it over the scales, it was just over 19,000 lbs...