You might consider air bags from Air Lift Company. I used them on my 4Runner and will be getting a set for my new Taco soon. I also carry heavy loads quite often and am looking at some utility equipment for the bed of my truck. New springs and air bags are the direction I'm heading.

Zuk's application is really quite ingenious, I like it! <img src="/forums/images/graemlins/kewl.gif" alt="" />

Mike