I have some experience with motorcycles and boats - not RVs per say, but I suspect it's the same.
Manufacturers will force unsold, previous year's models - and often unpopular models - to dealers when they order popular models. For example, Mr Dealer, if you want 5 Roo 23SS, you need to take 1 of these Model XYZ.
Manufacturers will then incentives dealers on these unsold units with additional discounts, coop advertising funds to help move them and so on. They will also often help with the financing - called floor plan - and often pick up the tab on all interest charges. They will keep doing that until it's sold, often providing very, very deep discounts to some very unpopular models.
Eventually they will be sold.
Denis & Diane
* Happy Campers *