Federal law states that the "finisher' of an incomplete build dates the vehicle. A previous poster said that "you can" title it at the newer date. No, by law it must be titled at the finisher's date of completion. A 2018 chassis completed in 2019 is a 2019.
When transferring ownership my VIN listed the coach as an 08. The Minnesota title listed it as an 09. California DMV wanted it titled as an 08. AAA acquired the documents necessary to prove my situation and have my title changed.
Accept nothing less. The manufacturer of the coach can provide you with the necessary documents to prove that point. It's not a choice, it's a fact.
My insurance covers my coach as an 09 at it's true value. Maybe discounted internet companies choose to do otherwise.
I have been seeing insured having issues with low cost internet insurance advertised on TV. When it's time for a claim they are difficult to deal with. My agent is down the street from my home and available to help.
As far as replacement items for the "house" they are easy to obtain, chassis parts as well, the difference in years doesn't change much with the Ford's.