I'm pulling a 40 ft Big Country 5er with a F-350 SRW 4X4, extended cab, 8 ft bed, 6.7 diesel. Handles great. Not a problem. I've pulled it on flat grounds and thru the CO Rockies and during some strong winds, head wind, tail wind and side wind. Never felt the need for a DRW. The SRW handled it fine.
Prior to this F-350 I pulled it with F-350, SRW 4X4, 4 door, 8 ft bed, 7.3 diesel. Rode great and never a problem pulling the 5er.
Major difference between the 2 trucks was getting around town. The 4 dr 8 ft bed took forever to make a U turn where the extended cab turns sharper. Don't really notice any difference pulling the 5er tho as I haven't needed to do that sharp of a U turn with either while pulling.
The SRW is a lot nicer getting around towns, parking, or hitting tight spots. The dually isn't that much wider but it's surprising just that little bit makes a major difference getting around. I've had my last dually. SRW for me.