Idk how big a boat you are towing, but coming from someone who is not one of the weight cops on here, any TC and a trailer behind does not scream 1/2 ton to me. Unless you want to do a bunch of suspension work and worry about the light duty rear axle.
Plus you said you're getting old. Do you really want to deal with every ting that comes with a pop up vs a hard side?
Now I have a heavy camper and the trailers I pull (boat or snowmachines) are 6klb plus.
I wouldn't dream of torturing a gasser with that load. My F250 6.2 gassers struggle in the mpg and hp department with 1/3 the load in the bed, 1/2 the trailer load and less wind resistance.
Unless there's a compelling reason to ditch your diesel, you already have a free truck that is more capable than a gasser.
At least get a 2500/3500 gasser. Do you want your last truck/camper setup to be comfortable or barely adequate? Sounds like you have the means to be comfortable...
Based on your previous post, how do you propose to reduce your footprint? The same configuration 1/2 ton vs hd pickup has essentially the same dimensions save for being a bit shorter in height. Cc, ec, sb, lb whatever. Trucks are the same size. Just the 1500s are wimpier.