Do you even know what you are looking at? Putting 15K down on a lease is never a good idea but this is almost 9% interest too (what is buy rate MF?)…horrible! The RV looks solid but have you confirmed what it should be? If these things really hold value maybe explore a buy of low mileage used.
Better for you to calc a target payment/DAS and make offers than just rely on dealer quotes where they are totally in control and especially if you don’t understand the numbers.
At least learn how to play with this: