If dually trucks only downside is that they cost a couple thousand more to buy and need an extra pair of tires then why do you suppose that 99% of the trucks on the highway are SRW pickups and why are 80% of the people pulling 5th wheel trailers using SRW pickups?
A DRW pickup is needed for a camper setup that is going to way in excess of 4500 lbs. but that is a small minority of truck campers. Current 3/4 and 1-ton trucks from GM exceed the 1-ton trucks of 5 years ago in every regard and will handle any 10' camper being sold today. Ford and Ram make less capable 3/4 ton trucks for marketing purposes but even their 1-ton SRW trucks have enough payload capacity for all but the 11' campers - where you do gain that super critical dry bath.
As for general hauling other than campers how many people put anything even close to half the payload capacity of their pickups into the bed? I can see no benefit of a large and wide DRW pickup with a huge turning radius and a 11' slide in camper over a Class C motorhome and quite a few big drawbacks, especially in terms of available and easily accessible cargo space.
This is really a great example of rationalizing a purchase decision that has already been made for largely emotional reasons.
