I pull a 40' with a SRW, short bed, crew cab, diesel 2013 GMC. We live in the northwest and travel to AZ. Nothing is flat. I put the cruise on 65 and sit back and relax. Does some down shifting in the mountain passes and a steep hill at times but never seems to strain. Went with the GMC after problems with my F-350 Ford. I like fords but I decided to go with a combination of long term proven performance in engine and tranny this time. The truck is easy to park, fits in my garage and is comfortable. I don't see the need for a dually unless you get pin weights in excess of 4000 lbs or need pulling trailers >18K. Everybody has their own comfort level.