Personally, I think it is really a matter of preference. Both can be safe and handle well, but the SRW will likely need significant mods to get there, whereas the dually may be able to do it stock.
w.r.t. lateral stability, I would agree that the extra rear track width of the dually is hard to make up for with suspension mods on a SRW. If you don't mind the DRW and can get a good one for a reasonable amount...go for it.
KD4UPL wrote:
I carried my Fleetwood 11x TC on a 2007 3500 SRW for a couple years. Then I switched to carrying it on a 2005 Chevy 3500 Dually. The difference in handling, stability, and ride was immediately obvious. The dually was far superior in every way to the SRW. I got exactly the same fuel mileage with both trucks, 10 mpg on diesel. The only real difference in the trucks was the SRW was a regular cab and the dually was a crew cab.
I don't care how many reasons you want to give a dually is the only way to go for a truck camper.
I daily drive my dually. It goes thru bank and restaurant drive thrus a couple times each week. It fits in parking spaces just fine.