I am new at the RV world but not at towing. I thought I would share with the poster asking about the Mega Cab Box and towing. The Mega box is 6'4" like you mentioned. Many I have asked and read post from here and other places say it widely depends on the RV your pulling and that the Heartlands have been compensated to handle short bed truck up to 6' and still allow a very good turnign radius 80* or so. where it gets close is on unlevel ground, if your backing up for example and the trailer is going up hill and the truck has not reach that grade yet the RV nose gets very close to the rear window if your turning. Many still say they have no problems but if your concerned or do a lot of tight maneurvering jsut grab a slider hitch. I was looking at the B&W companion slider. It works in conjunction with the B&W flip over gooseneck, minimal holes in the truck bed, nothing in the bed when you not hauling and you have every hitch needed. Unfortunately its not available for my 2012 Mega just yet but they have pricing for it so hopefully it will be out soon as family and I are looking to but the RV and make our first 5500 mile journey mid June. Hope that helps some