There is a lot of misconception about what a WD hitch will do for you on this forum.
The best set-up for braking and handling for a car or truck, whether it be a race car or a truck towing a trailer is a 50/50 front to rear weight bias.
The reason people put sand bags or big medal plates in the back of their pickup in cold weather is to get the weight bias corrected in a light in the rear truck. Trucks are light in the rear because there is nothing back there except a big empty box.
When you put a light trailer with a light tongue weight on the back of your truck you are correcting the poor weight bias of your truck. If you put a WD on a setup like this you are jacking weight off of an already light in the rear end truck and putting it on the heavy front end. This is not what you need to do.
I have a real heavy diesel truck and a pretty light trailer. Here is what I do. I have a WD hitch on my trailer and I use it. I do not transfer any weight to the front of my truck because that would be silly. I hand tighten the chains only. The chains are just snug and that's all. With this setup, I will not transfer any weight (remember I don't want to) but it will take most of the porpoising out of the setup.
This is the best setup for getting the weight bias and porpoising correct.