Start with searching these forums for Expedition being in threads. There have been a handful of related posts in the last couple of weeks in the Travel Trailer section.
I have a 2013 Expy with a 6,000# loaded trailer and would not dare go larger at this point. Either my WD/Anti-sway is not up to the task or I'm too light on the tongue. I'm not happy/stable above 60 MPH.
Count on putting 1,000# or more onto the dry weight before being road ready.
You'll probably be happiest with a 3/4-ton pick up or with a 2500 Suburban.
2013 Heartland North Trail 22 FBS Caliber Edition
2013 Ford Expedition EL with Tow Package