The VIN is assigned by Ford and thus will only describe the Ford chassis--when you look up a VIN decoder.
A phone call to Thor
with the VIN will tell you what model year the coach is.
Once you own it you can log into Thor's owner resources page (with the VIN) and get a wealth of information about the coach (manuals, diagrams, serial numbers, etc.).
Typically Chassis sit around at the plant (for up to a couple of years) before a motorhome is built on top of them. Thus the VIN very well may say 2015 for a 2016 (or even 2017) coach.