You could write your own prologue, anticipating how you think the series ought to end? In your, y'know. Copious free time.

(Personally, I never touch sample chapters of books I know I'm going to read; I want the whole thing, not a taster. And I never touch sample chapters of books I don't know I'm going to read, because I might want to read on, and then I'm stranded; or else I might not want to, and then I've wasted time. I am ... not the ideal market, for the sampler industry.)