>>/34011/
> or upload it other sites, forums, imageboards on the tor network
Easiest way is to find a file sharing .onion address, but if you just drop a .pdf there nobody will read it. I guess what you want is a backstory of the book circulating in the Deep Web for some time prior to official publication? Then you'd need to find some forum and distribute and discuss it there. Preferably a forum about books or your book's theme.