Yeah, indeed. The word to eject from the process is "formal", not "documentation". Write stuff down however it works for you: be it email, IRC logs, napkins, whiteboards, whatever. Refine as needed. Write summaries every few ideas.

If the problem is of the right size, bang out prototype scripts and let these serve as "documentation" too.

But scrap the endless cycles of proposals, reviews, designs and revisions. Do that stuff implicitly.