Why not both? Make a custom domain for the book, then treat your own site as if you were guest-blogging on it to pump link juice to the custom domain.
That way, your venture ends up with the combined page-rank of your personal brand and the exact-domain bonus. (Whereas if you just redirect from one to the other, you lose one or the other.)
That way, your venture ends up with the combined page-rank of your personal brand and the exact-domain bonus. (Whereas if you just redirect from one to the other, you lose one or the other.)