I was wondering if it is bad for a pickup truck to keep a heavy load in the back (e.g. 1800 lbs) for prolonged periods of time (e.g. 2-3 days), assuming the truck is not in motion. The disadvantage of driving with that load are obvious, my question refers to being stationary. E.g. is it bad for suspension, chassis, etc.
The correct answer will depend on the size of the truck. As long as you have not exceeded the load capacity of the chassis you should be fine. However the longer the springs are the compressed to their maximum deflection the less likely they are to return to their unloaded shape.