If your truck is in good condition I wouldn't be concerned at loading 1000 lbs. The ratings on mechanical items are often conservative. Over engineering and under rating prevents lawsuits. Look at the new "half ton" pickups & their rated capacity. The new Silverado 1500 has a payload capacity over a ton. Google the payload capacity of your truck and go from there.

Save a life, adopt a senior shelter pet.
The three main causes of blindness: Cataracts, Politics, Religion.
Name your dog Naked so you can walk Naked in the park.