Put ~700 miles on my truck this weekend, Fuel consumption was a little high due to just hauling ass but got almost 12 towing Sam's buckwheat and ~15 unloaded.
The 37's are staying, turns out most of my issues were caused by tunning and have now been fix. Better drop hitch, air bags and gears will still be going on in that order. It's easy to see some hotter EGT's with the lower cruising RPM's, but that's just fixed by speeding up
Couple poser pics
BTW, Sam's has a really amazing place
For comparison, my place which is only 300 miles west (should be one tank):