That's exactly what I did. Ordered a 2x4 SV diesel with upgrades in the beginning. Read issues w/ early releases, truly evaluated needs, (cause I wanted a diesel, BAD) and decided to go gas, I stepped up to a gas Pro4X w/ utility package, (which the RockFord Fosgate system is worth the money alone,) for LESS money.
My daily trip consists of a 12 mile trip through town, round trip to work and back, and any other short trip I may do, I'm averaging 13 MPG. Have been on Interstate a couple times at 75 - 80 MPH, showed 16 to 19 on computer. Have noticed as high as 22 when running 60 ish.
Have pulled my boat, 2200 lbs. hardly noticed load, not much difference in mileage. Pulled travel trailer, 4500 lbs. with 1000 lb. golf cart in bed, for a short test run, without weight distribution hitch, truck sat down about an inch and a half or two, at or just below level. Truck had plenty of power, very stable and confident, didn't track mileage as trip was only about 10 miles with stops and goes.
Will get it on the road with a trip to GA the end of the month, then I'll report what I get on that trip, approx. 750 miles.
I think I've said it before, but, I love my truck!!