I currently own a 2015 GMC 3500 single rear wheel. I carry a Hosts Cascade. I have done some significant mods to the truck, blistien shocks, heavy duty Timbrens, helwig sway bar, lower stable loads an...
The drw will carry it, but you might want airbags or similar to level it. Also, the tendency is to carry more stuff when you can. That will cause more suspension deflection.
I think the general rule of thumb is drw will cost 1 to 1.5 mpg with the same gear ratio, or more with a higher number ratio.