Lots of great advice. In 2019 I swapped TV's to a 2018 Ram 3500 dually MegaCab because I got a great price the left over dealer inventory.
A co-worker has a 2015 Ram 2500 Cummins, so I had quite a bit of time looking under the hood and many discussions over the + and - of the Cummins 6.7L turbo diesel. He was very knowledgable - He worked in commercial pickup trucks sales for years, completely spec'd his own truck from the dealership he used to work for. I learned a lot from him before my own shopping experience.
Lots of folks are reporting great results with the 6.4 HD gas engines. If you decide to go diesel you should opt for the 4WD. The reason is that the front end is quite heavy. Having drive wheels up front can help you out of a jam. My buddy says the front end sinks fast. He wound up in some real boondocking situations where the 4WD saved his butt.
I had to go through a detour situation where I wound up driving on old secondary road/streets that were missing pavement for hundreds of feet at a time. Just rolling along in FL white sugar sand dragging my camper behind me. Being able to shift to 4WD provided a lot of piece of mind and no question about traction as the front end plowed through the sand.
I'm not a fan of the Cummin's engine redesign in 2019. Yep it is stronger and makes bigger numbers. But to get those bigger numbers Cummins shifted to the Bosch CP4 self-destructing high pressure fuel pump. The 2018's have a Bosch CP3 pump which is much less susceptible to failure from US USLD. You can mitigate that risk by running lubricity additive. Being a "winner" in the torque and horsepower race (especially with the numbers as high as they are) is not where you want to be with it comes to how you run your diesel TV.
Pushing big numbers just leads toward expensive repair bills if you become a number/tune jockey. I've seen a lot of people with legitimate regrets after choosing to go down that road. You get to choose your own adventure. Choose wisely. Stock tune / Stock config is more than adequate for any HD truck (gas or diesel).
Hard to beat 1 Ton cargo capacity (even with the diesel penalty). You don't pay much of a premium for 1 ton over 3/4 ton trucks. Good luck with your shopping and decision-making. You certainly don't need a 1Ton. But you could always trade up campers without any concerns about capacity out in time. . .