I've got a set of Firestone air bags in the back of my truck. Before I ever installed those, I had a 2,400 lb. pallet of coal back there that I took about 30 miles. '07 Silverado 1500. Handled it very well.
I've overloaded many a vehicle. The weight carrying capacities of trucks today factor in liability #1, and #2 worst case scenario, like doing the 80 mph speed limit out west and having to jack your brakes to the floor for an emergency stop. MA has some of the slowest average speeds in the nation, so I can get away with it here - just got to ALWAYS pay attention, maintain your equipment, and take your time. Not advocating taking chances - just saying not everyone can afford a 3/4 or 1-ton truck - gotta do what you gotta do to keep the house warm.
I will say that the '07 handles the load MUCH better than my '94 did. Could have been because the '94 had well over 250k on her when this pic was taken.
3k pounds in back here: