That’s not how the mechanics work. The weight on the tongue depends on how far away from the axle the weight is loaded, both forward and back of the axle (fulcrum), even if there is always 60% forward and 40% rearward. Think of a 60-pound kid and a 40-pound kid varying their positions on a see-saw.
I figured they were talking equal distances and not silliness like 40% of the weight 1mm aft of the axle. Their setup was equidistant.
Which shows how inadequate it is to say percentages of the load, when position matters.
Anyway, my point was that in their setup, if the load was 100g, there wasn’t 60g of tongue weight, it was more like 20g.
The recommendation, as long as I’ve been trailering is 10-15% of trailer weight on the tongue (hitch). I’ve measured mine and my current rig is 8200 lbs., with 1100 lbs. on the hitch. Near the high end of the range.
My experience with this particular trailer has shown a tendency to sway, probably due to it’s 36’ length. It also has a V-nose front, which may exacerbate* sway from passing semis. I’ve had 2 travel trailers and 2 fifth wheels, and the fivers simply don’t have sway at all (ime). I attribute this to their even higher tongue weight percentage (and forward CG).
*I mentioned the swaying tendency to the aero guys at work and they came up with a complicated model showing that bow waves from passing trucks actually generate lift on the opposite side of the trailer. This “pulls” the front of the trailer away from the passing truck for a moment, which turns the rig toward the semi. This is exactly what I was noticing – the truck steered towards semis as they passed and required correction. I eventually abandoned the ball hitch and installed the trapezoidal hitch mentioned above and is solved the problem completely.