Good point on Payload. Looking up the specs on the 2019 Expedition (https://www.caranddriver.com/ford/expedition-expedition-max/specs) the maximum payload is 1758 pounds. So a maxed out trailer weight would only leave me 670 pounds for humans and stuff. You're right, that is cutting it close.
I do gain more weight allowance if I don't load the trailer to its maximum, but because the tongue weight is such a small percentage I don't gain much. If I load the trailer to 6800 pounds that allows for 774 pounds in humans and stuff. Hmmmm... that might be a limiting factor.
