>using anything but plain text files
I have no idea who that is.
You could just send them the .tex file? Isn't that how scientists do it?
>Publishers don't accept PDF's
OP are you retarded? You send in the LaTeX code, not a damm pdf
Nope, most major non-academic book publishers/agents/editors only accept .docx
pandoc can work with .docx, it can convert to-and-from .tex, template them, the works.