You're comparing purchase price vs mileage and capability.
And you already know the answer and the answer is a compromise either way.
Personally, I'd go diesel for that duty, but I can afford it. Had some neighbors in AK who settled in next door after doing the same gig, year on the road with a camper. Except their combo was a F150 Eco boost and a large TT. They did just fine and so will the gasser.
If you want the 6.2, it's bulletproof. I'd make sure you end up with the 6r140 vs the 100? Trans. At some point, Ford started putting a lighter trans behind the gassers, I think just in the F250 models.
Simple, powerful enough, but not great compared to the diesel, 6.2 is the safe, easy, relaible, simple choice.
On the flip side, you'll be sucking down petrol to the tune of about 7mpg pulling the 5ver all over. Had 2 of them company trucks and they'd pass most things except a gas station. I'd consider a gas slip tank for long journeys if I owned one for personal use.
Diesel, yes there's the possibility of emissions issues. But not a great risk, especially towing. That's what keeps them healthy. Only thing I'd doo is put a CP4 bypass kit and think hard about a '15 or newer model vs the older 6.7s for a host of other non critical, but advantageous reasons.
And your 7 mpg will turn into 10+ with the diesel. Empty, the mileage will go from 13-14 on the gasser to 17-18 on the diesel.