As with most situations, secrets don’t like to be kept hidden away. I don’t know how anyone expects to keep secrets anymore. Adopting a whole new identity would be hard enough for non-famous person, much less an author who was actually trying to get noticed. As for the question - publishers are as easy a mark as any of us. We all get sucked into a good story. Why not just write the book as a work of fiction? I just can’t imagine trying to live such a lie. (who the heck has the time and/or energy for that?)