The 2014 EL with HD tow package has a max loaded trailer spec of 8700#
NOTE: the vehicles GCWR is 15K pounds,
http://www.ford.com/resources/ford/general/pdf/towingguides/14_Expedition_Sep11.pdf
FYI, you can get into a 28 foot quad bunk ultralite Bullet (287 qbs) that weighs 5485# dry. You can figure, by the time you put in all the stuff you need, add 1000# to that number.
On our Kodiak, with Four Teenagers, two adults and a dog, the trailer all stocked for a 2 week camping trip, with everything you can think of. Chairs, coolers etc, added exactly 1000# to our trailer.
So if you take that bullet add the 1000# of gear, so 6485 total trailer weight, you still have and extra 2015# of capacity on your GCWR, that is more than enough safety net to take your family in your expy. and not make them follow in a car.