Just to throw out something here. In 2011 I bought a new Ford F350 LB CC King Ranch with a 6.2 V8. Short of having a diesel it was about the heaviest F350 that you can get. In 2013 I put a 3000# Northern Lite camper on it and my wife and I along with our 40# dog went to Alaska in the rig. Now loaded this camper was right at 4000#. I towed our 17' boat for the first 2000 miles to Montana. The total trip was over 11,000+ miles and when we returned we figured out the mileage for the entire trip and it came in at 10.2MPG average.
So as you can see I was carrying a lot more than you are looking at and it still got as good of mileage as the one post on the EB3.5 F150. My truck GVWR was 11,200#
On one tank of gas one time I got over 16 MPG empty. It has 4.30 rear axle ratio.
This is just to show you don't have to get the lightest pickup to try and get some good MPG especially when you are also looking at hauling a load sometimes
The only thing I did to the F350 was add Stable loads to it. After we got back from Alaska I did add 19.5 tires just because I was getting right at the limit on the stock tires.
