Bed length - long bed since it will carry any load better, will have a smoother ride, provides more bed space, will not require a slider hitch for the FW, and you really won't notice the turning radius difference.
If a TC is any possibility in the future, a 1-ton for sure. You will NOT be able to carry a camper in a 3/4 Ram due to the coil springs. The coil springs just aren't designed for carrying heavy high COG loads.
Truck camper is a loooong shot as DW does not like them.
That's what my wife use to say as we were rolling down the road with a 35' FW in tow. Then I bought one to use hauling my jeep to the trails. After the girls and I convinced her to take a trip or two just camping in it, she decided it wasn't that bad and the FW was soon sold. That was 8 years ago and we are still enjoying the same TC and have no plans anytime soon to switch back to a trailer. Not even after I retire in 3 years.
If you plan on retiring in 5 years and doubt you will be able to make another large purchase after retirement, then I would wait until your last year of employment before buying. It's going to be hard to make the one truck last through all of your retirement years.
I have the basic Ram truck you are looking liking and drive about the same: 2015 Ram 3500 SRW 4wd long bed, 6.4 hemi,3.73 gears and drive it daily the 10 miles each way to work and my run around vehicle. Difference is I moved up to a SLT for a couple thousand more because we felt the options on it was the cheaper way to go. Of course, I did want the chrome appearance package on the Tradesman and the power seat with fold flat rear eat which wasn't available on the Tradesman, but got a few other features like power sliding rear window. I really like the rear window because I like riding with the windows open and being able to open it gives a nice breeze through the cab.
I have 43k on the 6.4 and really love it for carrying my 2,400# TC. I had a 2004 Cummins before so know the power of the diesel. I feel that the 6.4 w/3.73 gears is good up to about 8 or 9k and the 4.10 up to about 10k, maybe 11k. After that, it should be the diesel. With detailed fuel tracking of the old diesel and comparing to the detailed tracking of the 6.4 carrying the same exact camper, it has cost me about $500 over the 42k miles because diesel has about a 10% premium. I did not want the high repair bill if the diesel had problems, especially with all the expensive emissions.
