I can only say from my experience of owning a '97 Ram 2500 and my current 2000 Ram 2000, I have not experienced any death wobble with either of them. The '97 had a FWC Grandby and loaded up, sat right around 8600 lbs. My 2000 has a Northstar TC800 and will be a few hundred lbs. over the 8800 lbs GVWR.
Both of these trucks are 4x4, extended cab, long bed trucks. My guess is folks having issues with death wobble after putting a hardside/popup camper on, likely are short bed trucks with campers that have a lot of weight behind the axle. The more weight you end up with behind the axle, it lightens the front loading on the axle and in turn, likely will cause a death wobble.
IMHO 1/2 ton and lighter duty trucks, should not have any type of slide in camper. They are just not designed for that use. I am also not a big fan of short bed/short wheel base truck with slide in's. It typically puts too much weight behind the axle, which is bad for handling/safety. I believe in the "just because you can do it, doesn't mean you should" mantra.
As for the modern Rams, I think a lot of them are running rear coil springs, so I don't have any experience with them. Both of my Rams use leaf springs.
Buy the right truck, for the right camper and you will be good. Figure out your camper first, buy your truck to match. Too many do it the other way around and find they bought the wrong truck.