Your TV has a 55 sq. ft. frontal area limit. Given that the x19H is 8x8=64 sq. ft.
Though this: http://www.fleet.ford.com/resources/...e_r3_Nov12.pdf
Shows that an F-150 maxes out at only 60 sq ft.
You might want to consider the 7' wide trailers, though even those are 56 sq ft.
Ford doesn't show a separate max TW when using a WDH on the Transit like it does for other vehicles. So your max TW is 510#
The x19H has a dry weight of 3665# and a dry TW of 400#. Add in 100# for 2 propane tanks and a battery and you're pretty much at your max. Theoretically, with the HTT GVWR of 4950# you could have a TW from 500-750#.
How you load the TT affects TW. But you'd still want between 10-15% on the tongue.
Additionally, with that size trailer you'd probably want a WDH and from the TV perspective, the 100# WDH is extra TW.
You mention GCWR of 11200 and GVWR of 8550, question what's the actual weight of the TV?
I'd suggest taking a look at the TowingCapacityWorksheet on this page..
RV Itch - Resources
I won't say you can't do it...but you'd be pushing the TV if you do. (I have experience with that!
From what I've heard about the Ecoboost, I wouldn't worry about the engine. Instead I'd be more concerned about the transmission. I didn't see anything about a factory transmission cooler. I'd consider putting on an aftermarket one; while you're at it put on an oil cooler to perhaps.