It's unclear if you want a new truck or new to you truck. In the older than 2008 trucks, the only viable SRW choice is a Ford if you want the highest payload. Unless there is some reason you need a diesel, I'd go with a gasoline model '05-'07. I can't tell if you plan to go over mountains much or not. If not, a gasoline powered truck should be plenty.
If you are truly wanting a "new" truck or newer than '07, you have a lot more options. I would make sure the width of your camper will clear the bed of the GM models though. I prefer Ford trucks, so that's what I'd buy. Ram and GM newer trucks are ok, but I just don't like their looks internal and external and have no reason to move away from Ford.
As far as 6.0 PSD is concerned. They haven't made them for a long time. All of the issues are well known, and the models that had the most issues were '03-'04 which were built over 10 years ago. For the other choices in the timeframe, you can expect issues as well both by design and age. Injectors can go out on any diesel, so if you are going for an old diesel, I don't see one as being that much better than the other. All of the newer model diesels seem to be doing quite well from all I've read.