That's interesting. I've always heard that 10% of the loaded trailer weight should be on the tongue. Maybe they err on the high side because most people are not going to be able to get so close, and too much weight on the tongue is way better than negative weight?
I'll never forget the trip I once made hauling some lumber on a (U-Haul) car hauler. The lumber was up to 2' longer than the deck, and since it had that railing both sides and across the front I couldn't move the lumber far enough forward to get any weight on the tongue. VT to WV I couldn't exceed 50 MPH without getting terrible trailer sway. Thankfully, at the time the speed limit was still the Federal double nickle so I wasn't too much of a road block.
