If its being used only for towing, go with the dually. I am lucky enough to have the truck for towing purposes only ( and the occasional errand where you may need a truck ), and have a normal daily driver.

I tow a 24' tag, loaded around 9000 lbs. When i hook it up, you barely even know its there. towing, stopping, everything. with my single rear wheel 3/4, you Definately knew it was there. i went the route of inexpensive. i have a 95 Ford crew cab 8' box 1 ton 4x4. its a big ass truck, but considering the amount of usage i give it, its perfect.

good luck