Okay, it's time.  Finish writing the book, all of it.  As a writer looking for a first publication, this is the only reasonable approach, and the only real power you have.  This is true unless, of course, you happen to be in the middle of a scandal in which the press has not yet found out all the details, in which case a publisher will find a ghost writer to pretty much write the book for you, and very quickly.

• ADVICE. Book proposals, sample sections, and ideas are all fine, but are not the normal province of creative writing.  They fit more into professional and niche writing, or journalism.  With a finished manuscript, rather than a proposed one, you are not operating under a work-for-hire arrangement.
  
• The finished manuscript is a great freedom and a great burden both.  It is a freedom in that nobody tells you what to do; it is a burden in that you have to then find someone interested in what you have done.  There may be no ready-made market for what you do, especially if your work is cutting edge, regardless of genre.  Still, the genres of poetry and fiction have managed to persevere.  Good writing is intrinsically valuable.  Never waver on that point.