I think for what you describe you might be well served by a half ton Ford with the 3.5 Ecoboost. My Grandad and a good friend of mine both have them and pull campers and assorted stock and utility trailers. They will flat pull, plenty of power. Both get 8-12 mpg towing depending on wind and speeds. Grandad will probably never buy another truck, he’s 87 and starting to slow down, been nothing but satisfied with the truck since he drove it off the lot.
Buddy loves the ride, power, and mileage of his but told me recently he’s probably going to go 3/4 ton gas for his next one. His only complaint is that in some situations he feels like the truck is lacking in the stability department. Stiffer springs, more rigid frame, E rated tires, and larger brakes on the 3/4 should help with that. His camper is a 28’ bumper pull, so likely heavier and definitely more wind resistance than your box trailer.
Another good friend has a Raptor with the Ecoboost and 10 speed. We pulled a 20’ enclosed race car trailer loaded heavy to Colorado last year elk hunting with it. I was amazed at the way it pulled and handled in Tow mode. He is a big time farmer with a 1 ton Ford diesel of every generation going back to the first year Powerstroke and ending with a 2015 6.7 Powerstroke in his barn. He claims he’d give them all up for gas if Ford would make a V8 Ecoboost and put it in 1 ton cab and chassis.
