You delete the last chapter and equivocally claim it's a true story. You sell millions, then Peter Weir will adapt your novel. People will argue, and then later you can release the original ending and everyone will ignore it because it's really quite dumb. No answer is much better than a stupid answer.
Well, at least that's what happened with Picnic at Hanging Rock, which Weir adapted from Joan Lindsay's novel in 1975 and Lost in Criterion discusses on this week's episode. It still manages to be a beautifully shot and interesting film, despite the lack of resolution.