It is good that you are paying attention to the details; max cargo is one detail that often creeps up on people.
I would venture to say that many farmers and construction people ignore the max payload from time to time given the loads I have seen them haul.:B
Over loading the vehicle increases wear of course, and severe overloading effect handling and performance. But I have often wondered, over the life of a vehicle that is used daily for house hold purposes; such as work and running the kids around, how much increase in wear and tear there is due to using it as a TV.