That sounds like what I need. I have been using Latex (which I find distracting) and restructured text (which I am less familiar with at the moment) with Sphinx. How does Asciidoc compare to restructured text? Both were intended for writing documentation so are similar in capabilities?
Then again, content is king. Write it on napkins if you must. When complete, you can spend two days to transcribe to whatever format the publisher requires.