I can DD my dually, I really have no real issue doing it. My biggest issue with my truck is that it's a pretty rough ride empty. I can even go through a drive through.
The biggest issue is that for drive through is if your mirrors fit your duallys will fit. What people forget to do is drive past an obstacle and then turn. Lots of people turn too quick and hit the dually fender.
My mpg experience is different as I drive a gasser. Expect about 11-12 mpg in a gasser highway , 9-10 city and 7.5-9 mpg towing
Otherwise no problems.
Thanks
Jeremiah