^Yeah that!
You've pretty much answered your own question in your first post though.
Gas vs diesel? Sure the newer 1/2 ton big engines pretty much match diesels for empty fuel mileage. HD gassers do not. Hook a trailer and you'll still have a significant difference in mileage as well.
However, the decision financially also much depends on your situation with work. Is your truck all out of pocket or do you get a vehicle allowance, fuel paid, etc? Also how long do you plan on keeping the truck?
If you're not footing the fuel bill, with the high miles you drive, gas v diesel doesn't matter for mileage. If you're paying for the truck and maintenance then a gasser will be cheaper. But if you're planning on keeping it a long time, then the diesel may pan out financially.
So diesel is the obvious choice from a power and finesse while towing standpoint, but I'd run the numbers based on your situation.
