Math from your numbers leaves an 8040# travel trailer. You must have quoted the factory weight listing for 6600#. When crunching non toy hauler travel trailer numbers, its best (IMHO) to use the trailer GVWR as a closer guesstimate when loaded for camping.
A hefty load for an Expedition but doable if properly equipped. Still a hefty load exceeding factory tow capacity for probably 50-60% (SWAG) of F150s.