Am I stretching my ecoboost limits?

While you are stretching the limits a bit it all depends on HOW you travel. ON my 8,000 lb. fully loaded trailer by the time I get the truck loaded with cargo and people, I am moving about 10,500 lb. against my 11,300 lb. tow rating. The trucks handles that weight very well but would expect that to at least SOME degree you also would be carrying stuff in your truck while towing. ALL of that weight goes against your rated maximum trailer. I"d also be considering just what the actual tongue weight will be when you're fully loaded because you MAY not have enough receiver capacity to handle it. The EB HD model like mine is delivered with a 1,200 lb. maximum tongue weight and that's just 50 lb. extra for my Rockwood. I would expect that your trailer would be heavier in the tongue than mine (as much as 15% of the GVWR of the trailer.

One thing to consider about the Ecoboost. You will nave almost NO diminished power at high altitude so towing only in flat land should not be an issue. I climb 8% grades in 4th gear adn 1800 RPM up to over 12,000 feet elevation.

Good luck / Skip