I love all the insanely high mileage numbers. Somebody averaging 20+ mpg in a 8,000+ lb truck kinda cracks me up, 'cause it's obvious the truck isn't working. I'm all about freedom - if you can afford it, and that's what you want to drive and want to do with it, have at it.
I'm also all about OCD..
My '17:
80,922 miles
5,048 pulling an 8.5'x16' enclosed trailer, averaging approx. 5,000 lbs
19,142 pulling a 28' GN, loads all over the map, from approx. 6,000 empty, to roughly 20,000 lbs of trailer, skid steer loader, and attachments - roughly half of those miles loaded, and half empty
3,187 pulling a 36' fifth wheel
6,193 gallons of fuel
125 gallons of DEF
I've seen the 50-mile average numbers in the neighborhood of 20 mpg when running empty, but when you do other things with it, that number is meaningless. The concern over mpg is primarily a financial matter - cost of fuel per mile, per year, etc. This works out to a very tiny hair over 13 mpg for it's now 20-months-and-five-days career. Given what I've accomplished with it, I'm more than happy with that.