While it would be "fun" to do your math for you...
The 9200 pounds is a max, not planning number and the truck must be empty. You get a free 150 pound driver but few of us have been 150 in years. Every other pound for the firewood, camping stuff, dogs, McDonald's french fries under the seat -- and passengers -- comes off that number.
Then there's that pesky 880 pounds of tongue weight. Expeditions weigh about 5500 pounds empty and GVWR is 7500 so only have capacity in the truck for about 1100 pounds of people and dogs. Four adults and their stuff will consume that.
Towing at or near the max leaves no reserve for high summer temperatures, long grades, etc.
All this makes my head spin which is why I formulated the
One Ton Rule. Simple, the trailer has to weigh no more than 2000 pounds less than the Max Tow Rating -- 9200 - 2000 = 7200 pounds is the max trailer I'll tow any distance.
-- Chuck