I have a F-250 4X4, my buddy has a Chevy 2500 4X4.
We don't check mileage, we tow campers in the mountains.
They both do what we bought em for.
A 3/4 ton truck is generally a better towing machine than a 1/2 ton.
You can put a bigger motor in the 1/2 ton, and the 3/4 ton
still generally outperforms it.
Partly because of the weight of the truck, and the suspension too.
When I'm towing, I fill up when I get less than 1/2 tank.
When I'm not towing I fill up when I'm down to about 1/4 tank,
unless I'm on the hway, then I fill up below 1/2 tank.
NO PROBLEM.