There is a lot of difference between trailers -- it isn't just the weight. I know my travel trailer is about the least economical thing out there to tow. With lower profile trailers, I have easily been in the 13-14 mpg range with my other trucks (haven't towed one over any distance w/ my EB yet!), even though they weigh about the same as my travel trailer. But with the travel trailer in tow, it is tough to break 10 mpg. Which is about where I'm at in the EB towing the travel trailer.
2011 F 150 Screw 5.5 bed EB XLT 4x4