The cabover camper folks clearly can relate to better stability carrying lots of weight from a heavy camper that is fairly high/tall on the truck. And, for a fifth wheel the pin weight can be significant for a single rear wheel truck. Most duallys have higher payload ratings than the exact same truck in the single rear wheel configuration. And usually a stronger axle. But, for a heavy cabover camper there is no comparison about the stability of a dually vs a single rear wheel truck. Handling is not even in the same hemisphere.
I have had both a 4000 pound cabover camper and now a 30 foot travel trailer and like how the dually also tows the trailer. It probably does not need a dually, but the dually certainly makes the towing more predicatable especially in strong winds. So, I plan to stay on the 'dually' side of any tow vehicle ledger.
My dually is a daily driver and I have not found the fenders to be an issue. They do not stick out farther than the mirrors and do not increse the already long truck. I am not a fast food or bank 'drive thru' person and I avoid as much as possible parking garages more for the height issue than length/width. Even in big cities like San Francisco the dually has not presented any issues that the same truck in a single rear wheel configuration would not also encounter.