You have a chassis VIN and a final vehicle VIN. The model year code for the final vehicle VIN will be the model year of the finished vehicle.
Chassis model years and VINs tend to change late autumn of the previous calendar year. Thus 2016 model years might begin production around October 2015.
RV model years tend to change early in the previous calendar year. 2016 model years, and 2016 VINs might show as early as January 2015.
For motorized RVs, it is likely that most of the production for a RV model year will be on a chassis of the previous model year. Almost all of the production of a RV model year, motorized or not, will be accomplished in the previous calendar year, on chassis with VIN for the previous model year. That is just the way it is.
You are fortunate if you managed to get your motorized RV titled for the finished vehicle model year, rather than the chassis model year.