In addition to our Airstream, I also have a 17' Casita that I use going to RC funflys where I camp at the flying fields. The Casita only weighs in the neighborhood of 3K pounds, but the tongue weight is significant at about 400 pounds, and I've wondered if a WD hitch would help the ride and handling when towing the little trailer.
So, I bought the single bar WD hitch from etrailer.com rated at up to 4000 pounds, and up to 400 pounds tongue weight, and installed it this morning. Very simple bolt-together assembly.
It has been a while since I towed the Casita, so I first hitched it up like I had been towing it, with a simple ball, and went a few miles down the road to get the "feel" for it again. Then I installed and adjusted the WD hitch, and towed the trailer over the same roads to see if I liked the improvement.
For a reference, I took a measurement of the ride height of the front of my truck without the trailer, and with the trailer on the simple ball hitch. I measured an increase in ride height of 1/4" at the front wheel well, which on a truck the size of mine is a considerable amount of weight reduction for such a small trailer. However, the tongue wight is significant. Then, when I adjusted the WD hitch, I simply adjusted for the same front ride height as before without the trailer, which insures the tongue weight is being carried directly over the rear axle, which by the way, is what GM specifies in their instructions.
I might mention at this point the hitch is very easy to adjust. Because the "J" bolt that connects to the chain is threaded for quite a way at the top, it's a simple matter to adjust the nut for the exact amount of weight distribution you want to get the load distributed. No more fiddling with bolts taking up half a link on the chain.
I can honestly say there is a very noticable improvement in ride, and I suspect handling would also be improved, especially if one would ever get into a panic situation. No more pitching and bucking on the bumps. Even with my long wheelbase heavy duty 1/2 ton truck, those things are noticeable and agrivating pulling the Casita. It is my opinion this is the perfect
sized WD hitch for trailer like the 17' Casita, or maybe an early model Bambi. If you are considering a WD hitch, I highly recommend this one.
Here's a picture of the truck and trailer in my driveway hitched up and adjusted.