The factory MSRP is supposed to include dealer prep, but not shipping. These pricing shenanigans began when buyers began to insist on steep discounts as the norm, i.e. they "learned" on the internet that they should demand 30% of MSRP. Few dealers have enough sales volume to stay in business at that price, so they came up with ways to make the deal appear attractive without cutting their margin too badly. Buyers who are focused on the discount percentage or the ad price too often let the extras slide right by.
Regardless, the only price that means anything is "out the door", which includes any & all dealer charges, taxes, tag fees, etc. It's also the only basis for comparing prices from two or more dealers.
Unlike with cars, there is no law requiring that the factory MSRP be posted on the vehicle. Many dealers make up their own "list price" sheet and it is often inflated with extras like "paint protection", "make ready", delivery charge", and similar wording. Ask the dealer for the factory MSRP sheet for that particular RV - some, perhaps many, will oblige. If they won't, you should assume the price sheet they have displayed is significantly inflated. Some the the factories, e.g. Tiffin, used to oblige if someone requested an MSRP price on a particular model/options, but I'm not sure which still do that. Some, like Fleetwood, let you "Build & Price" on their website.