[flybouy]

It's difficult to find info on a 13 yr old trailer but from what I can see it should be around a 6k trailer. With a 13% tongue weight should be around 750-800 lbs. That said, with a properly sized and adjusted wdh you should not have ant rear end "squat". The purpose of the wdh is to get the weight distributed so the front and rear axles equally.

Is the trailer new to you? Do you have anything else in the bed of the truck like a generator, tool box, cap? What are the bars on the wdh rated at?

I would start with a trip to the CAT scale to see where you're at weight wise. After getting that info If the trailer is overweight leave some stuff at home. If the tongue is heavy redistribute some weight. Once those issues, if they exist, are corrected then start at page 1 of the wdh install instructions and make certain it's correct.

As for your question on air bags... Most have a very low minimum inflation and should not alter ride height or ride when the truck is unloaded. They DO NOT ADD TO THE PAYLOAD CAPACITY OF THE TRUCK. In fact, they reduce it. Look at the yellow and white tire inflation sticker on the driver's door jamb. That line that says "cargo and passengers cannot exceed xxx lbs. Is your payload. That's what the truck had when it left the factory. Anything added to the truck comes off the payload. So if you added running boards, mud flaps, bed liner, bed cover, tool box, tools, firewood, an ice chest with drinks, ANYTHING placed into or installed on the truck reduces payload by the weight of that object.

Airbags are great in my opinion but if you need them to level out a truck with a wdh then something is wrong.