Sure, I can see going for the most complete solution. Now the bad news... all that understanding of axle
loads is still required to properly
adjust the WD system. On the other hand, adjusting any friction-type sway control component is essentially random.
I second Roger's point: you still need to set the rig up properly, regardless of whether or not you add on devices.
If you get all of the hardware, then take the rig to a weigh scale, you can find out both how to adjust the WD system, and whether you needed it or not in the first place.... now that you have the axle
By the way, the WD heads are normally quite long (due to the height adjustment which always comes with them), so it will likely place the ball further back than it would need to be without WD, thus increasing load transfer from the truck's front axle
to the rear. In other words, the WD hardware will increase the requirement for WD... which makes it easier to later rationalize buying the stuff!