Rather than buy a used mid-line RV, buy a used high end trailer. We bought our 4 year old Cameo ar 40% of new and it had barely been used.
For full-timing, the trailer will be heavy and I would start with a 1 ton dually diesel and no less of a truck. Sure you will see lots of folks out her pulling 36' plus trailers with a 3/4 ton or a SRW 1 ton, but they are most likely well over the manufacturers ratings for the truck. Remember to never believe the RV or truck sales person for towing advice. There job is to sell RV or trucks and not be your towing consultant.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot