got some hard numbers of my own.  very short ride, I'll see better after the upcoming 1,000mi trip. 
TT:  2016 Coachmen Clipper 17bh
TV:  2010 Jeep Liberty 4x4, 3.7L gas engine (21mpg highway not towing)
Most of the drive I had overdrive OFF, though this seemed unnecessary.  My max speed was about 60mph (maybe a little more when passing) but a lot of the drive was a construction zone, so was around 45-50mph.
today's drive:
73mi / 5.8 gal = 12.5mpgs
I'm pretty happy with that, hopefully it stays around there for longer trips!