It would weigh more, but it would be from all of the shite on the seats and floor.
My take on it is ,If the guls arent touching the body of the aircraft they support themselves, but if the air currants from their wings hit the air craft interiour they then apply force to the aircraft causing it to bear at least some of their weight.
Oh u r good!!
yes, its the weight contained inside, not necessarily the weight sitting on the floor