If you're not afraid of "twofootitis" you might consider getting a 3/4T gasser. It'll do great in the flat-lands where you do most of your towing, and it is adequate in the mountains.
If you think you MIGHT upgrade the camper in the future, may as well get the truck for it now. LOTS of people get JUST enough truck, then end up upgrading their camper, then they have to upgrade the truck too, and on and on and on...
I moved from a 2012 Sierra 1500 to a Ram 2500 4x4 with 6.4L Hemi when we towed our 28BHBE and my only regret was getting the 3.73 instead of the 4.10 rear end. Towed my 28BHBE like a champ all over the place. It had over 3300 lbs of payload capacity, so I never worried about overloading it, and it took EVERYTHING I threw at it and never even stuttered. 4WD came in handy MANY times, especially out at the deer lease; hauled 250 gallon water totes up hill-country goat trails with ease.
Of course, nothing pulls like a diesel. And I agree, if you're going to go with a diesel, you may as well go with a 1T. The diesel motor costs a LOT of payload, and going up to the 3500 helps make that up.
I didn't get a diesel when it came time for a few reasons. I have a VERY short commute, and the truck was my daily driver. Diesels need to run hot for some time or you'll have problems. I also didn't want to pay the diesel premium (in purchase price or in fuel premium) at the time. We only towed about once every 6 weeks on average with one or two longer trips per year. So my usage pattern just didn't support having a diesel.
If I were full-time, or we traveled a lot more than we do, or I had a longer commute, or I had other things to tow/haul heavy, the decision would likely have been different. But for what I needed, the gas 3/4T was perfect.
-2018 Greyhawk 29MV
-2020 Jeep Wrangler Unlimited (JLU) (Primary Toad)
-1994 Jeep Wrangler YJ (Secondary Toad)
-2014 Jay Flight 28BHBE & Ram 2500 6.4L CC 4x4 (sold)