The tire pressure label say 944 lbs, but the vin plate says 5124 GVWR, which is a bit over a thousand pounds (curb weight is just over 4000, depending on options). I've probably gotten close to that in my 04 DeVille with my late 450lb B-i-l, my sister and a trunkful of luggage on annual 700 mile each way trips to my brother's for Christmas. The owner's manual warns it may shorten the life of your vehicle to overload it, so it could be why I felt the need to trade it at 127k miles--something was off in the front suspension/steering. That was the only time the auto leveling compressor ran during a trip, which freaked me out the first time, but it didn't affect its operation afterward.
Be sure you have the maximum air pressure in your tires (should be written on the tire), distribute the weight as much as possible (put Fatty in the trunk), watch out for steep driveways (take them very slowly at an angle, if you absolutely must). Remember your handling and braking will be diminished, so longer following distances and slower speeds on curves are required. Acceleration will be affected, too, so no passing on two lane roads.