If the Travel Trailer you are getting has elect brakes You will need a 7 pin connector Depends on the wiring on the 05 but you may be abler to get a plug in adaptor that plugs into the main harness under the rear. I know that is possible for the 1st gens.
You should also consider up-grading to the heavy duty tow package for the expedition which would include a trans cooler, 7 pin connector, full frame receiver which you may already have. The TT weight is low so you may not need a Weight Distribution Hitch or sway control But I would suggest that you have them if you plan to go to a heavier trailer in the future.
I would suggest that you talk to the dealer of the TT and also ford for information.
But do check ford etis to see what you already have.