Good advice.
I too an planning on full-timing with a 3/4 ton (an 08 F-250 6.4l supercab LB.) However I'm planning on pulling a TT with it as the bed will only carry 2730lbs. Remember you will be carrying all your worldly goods so the trailer's CCC is important. Most people suggest no less than 3,000 lbs for a FTing couple. This will be your limiting factor when considering TTs as few (other than some toy haulers) have that much CCC. I'm looking at something in the 7-8,000 lb range as this gives me 3,000 lbs of carrying capacity before approaching my self-imposed 10-11,000 lb limit. (Ford suggests a 12,500 lb towing limit for my truck.) They also say it will handle a 15,900 lb fiver, but the pin weight of a trailer that large would easily exceed its rear axle rating.
If you are dead set on a fiver, I suggest no less than a 1 ton dually for FTing. We are choosing a TT because of the lack of internal stairs and my DY has a hard time negotiating steps (she can, but it's painful). Also we plan on carrying a couple light-weight motorbikes with us (150 lbs each) in the bed as they won't fit in the basement storage of a fiver. Plus fuel mileage (economy) is important to us (as we plan on traveling a lot) and the lighter we go and the less frontal area we have, the better the MPG will be. We are currently looking at the Keystone Sprinter 331RLS (we love the floorplan of the new 319MKS if it's within our specs), the Forest River 28VFKS Work and Play toy hauler and the Wildcat Maxx 28RKX.
Chip