I have been towing with my Megacab dually for 2 1/2 years now. It is important to note that the bed length is exactly the same in all Ram HD short boxes including the Megacab, which is 6'4". I think many believe the Megacab box is shorter than the crewcab shortbox because of the size of the cab but it isn't.
Our last FW was a 2005 with a fairly square nose and I had to use my slider hitch a couple of times while backing into tight spaces. Our current FW has a rounded front cap and I have yet to come even remotely close to hitting the cab of the truck with the hitch in the regular towing position. I think I could easily have a non slider hitch now.
We love the Megacab dually; the cab has tons of room including the ability to put suitcases BEHIND the rear seat. The rear seats also recline and our son just loves it back there. Starting in 2013, they have the same GVWR as the crew cab long box so they are pretty much capable of towing any RV out there. I have never had so many compliments on any truck I've owned as this one.
Let us know if you have any other questions and how you make out!