This sounds very similar to what I'm doing through my patreon, though I'm releasing the book (a collection of short stories) chapter by chapter. I'm still thinking of ways to integrate the book with my steemit account but as the platform is organized around the 7 day post life, and most of our feeds are far too saturated making most readers not entirely regular readers, I still feel a bit confused about how to share the book on steemit, as whatever I post will be buried by new posts. I have posted small excerpts and plan to post entire chapters, maybe even some bonus chapters on steemit when the time is right, Perhaps after I'm finished and re-edit I'll do the same thing and release it on more mainstream platforms (I might have some questions with the copyright process).

I'm also doing pay what you want and I think we are expressing very similar things, though I'm doing it through fiction. Feel free to check it out

https://www.patreon.com/thetree123

Are you on discord? it'd be great to share ideas about the best way to release stuff and maybe collaborate in the future.

I'm really looking forward to your book as well.