Truck Forums - Rear adjustable air shocks

I've just bought a 26' camping trailer that is tounge heavy for my 2006 F150 XLT. The trailer wieghts approx. 4,500 pounds. I have been looking for some adjustable air shocks to put on the rear to help compensate for the weight and make the trailer ride level and a search of the internet hasn't been much help.
Can I get some help finding this or something else that will work ? It needs to be "shade tree mechanic" friendly. I would rather do the work myself.
Would adding "helper springs" work just as well as air shocks ?