My apologies. I actually think you are correct.
I researched this most of the morning which included a visit to my dealer. They have two single-cab Tradesman's on the lot with 8-foot beds. There were no papers in the vehicles indicating that THAT vehicle was prohibited from a slide on camper.
However, I talked to several others who indicated that some 2500s were not recommended for slide on campers and they attested to the fact that some do get a separate piece of paper indicating it. However, no one I talked to could show me verifiable proof about which configurations are prohibited. I was told "special equipment" was required in some cases, there's a "Camper Guide," but no one could find it. I was also told that there's a sales code for slide on camper equipment, but they couldn't find that either.
What bothers me is that people in sales seemed to have vastly different opinions about this.
I did stop in and asked my trailer dealer if he had any specs on Ram HDs, but he refused to quote anything until he saw the GVWR and payload specifications.
But there are others on the web who, like you, are informed that at least some Ram 2500s are not compatible with slide on campers.
Regards,
Dusty
2019 Ram 1500 Billet Silver Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 3 June 2018. Now at 82990 miles