I have a 2012 F150 EB Max Tow Supercrew. I pull a roughly 7,500lb 32' travel trailer with it.
I am extremely happy with it. Would've bought a F250, but I wanted got be able to keep it in my garage. Glad now I don't buy the F250, since it would've been overkill.
I'm now looking at 34-36' toy hauler TT's in the 9,000-10,000b range, and plan to pull them with the same truck. That should tell you how I feel on the truck's capabilities.
As far as finding one, email Ford corporate truck sales(their "contact us" link is on the web site. Tell them you're wanting to buy a F150 Max Tow, but none of your local dealers are really helping out. Include your cell number. I got a call within 2 hours from a very nice lady who gave me the contact info for 2 dealerships who had the exact truck I wanted. Was flying from New Orleans to Nashville 2 days later. The dealership sent a sales rep to pick me up from the airport. Was home a little before midnight. Funny part, I get all the Ford service coupons and such in the mail as if my local dealer is the one in Nashville.
Get the 36-gallon tank. Don't even consider buying any truck for towing with a 26-gallon tank.
If you decide you want more power, look at the 5-star tuning programs and a SCT Livewire programmer. Not out for 2015's just yet, but on my 2012 I run 87 or 89 octane performance/tow tunes. No real change in MPG, but lots more power in the under-3000RPM range.