No, I'm 90% sure that's not it. I have one of those little Sherline (?) tongue scales. I think it's near 13% (still have to verify the trailer weight). This trailer had one of those heavy fold-down steel racks on the back bumper, with the spare on that. Removing that rack was one of the first things I did.
For now I will use the WD hitch, but I still consider it a kludge. Heavy, hard to remove for an old guy like me, annoying to hook up, puts a lot of strain on the hitch, greasy. It has a longer stinger which induces more sway, and the excessive weight way back there increases the very problem (lift in front, sag in back) it is designed to eliminate, so you have to put even more tension on the bars to compensate.
The real problem is having the attachment point so far behind the axle. Why don't truck manufacturers move the axle back a foot? Why don't they implement a Pull-rite type arrangement for the factory hitch?
Leaving aside the anti-sway property of my e2 WD hitch, there are other ways to reduce the front end lift with WC hitches that are not so kludgy:
1) Get the shortest possible stinger
2) Get a light aluminum stinger
3) Get a tongue scale and trim down the tongue weight to a reasonable minimum
4) Take some weight off the back of the truck; e.g. tailgate, bumper, and spare (either remove completely or move forward)
5) Add some weight as far in front of the front axle as you can manage
6) Get truck tires with stiffer sidewalls
7) Add helper springs or air bags to the truck rear suspension
8) Get a lighter trailer, or remove weight from the trailer
I realize some of these come with drawbacks too. Thanks for listening to my rant. :-)