Just some food for thought. During combat operations we were authorized to up the gross Weight of the AH-64 after the Army bought the extended weight and balance charts from Boing. Keep in mind that Boing sold the Army just what they ask for in the beginning. Knowing that the Army would need better performance, Boing, back then Hughes, built the aircraft better than the specifications and only sold the Army what they ask for in the way of charts. Now the Army needs more lift capability and Boing just pulls the charts and sells them to the Army at an exuberant fee when they knew all along it was capable of the extra weight and lift capabilities . Now knowing that I also know that aircraft manufacturers will give the customers what they want and no more. I can tell you that the one I currently fly can lift way more than it is certified for. I will go back to the airlines and ask you this. If the aircraft is certified for X gross weight don’t you think that the airlines would weight each passenger and piece of baggage?
Not smoke and mirrors just fact of business. If a client needs more gross weight payload you might be able to up the payload for nothing more than that extra fee for the paperwork. Been there and done that one.