Although I understand the concept of using his established brand to capitalize on his current readers, I would think he needs to reach far beyond his current readers to make a profit on a published text. In that case he needs a title that will draw new readers in. (He can tell those of us who read his blog what the book's going to be called, and chances are we'll just go out and get it, whatever it's title is.) Having said that, "Behind the Ambulance Door" sounds a little stiff to me, but I don't have a better suggestion!