alt Hacker NewsThat's awesome, can I ask what the topic is? What I did for "selling" the book was to create a proposal -- about 45 pages that has a skeleton outline of each chapter (it changed significantly during the end writing process but gave the publisher a feel for the topic), a sample chapter, and some more sales/marketing details like what are comparable books (and how well they sold if you have that data), who your audience is and how you plan to reach them (OP was in a great place having a following), why you're the right person to write the book, etc.
45 pages as a skeleton? Wow. I wasn't expecting that much! I guess your book is +120k words? Do you think having a clear vision/structure helped when sending it to publishers?
I think I lack all the last parts (that some publishers are requiring for) such as a social media platform to reach your potential readers. I find that a bit unfair because it means you first have to play the Instagram game and once you are popular there, you can write a book.
If you give me an email address I'd love to tell you more about my book!