I did it -- I juggled writing, event planning, work, and promotion plans, and I managed to finish the book.
I wanted to wrap it up in November, but I just wrote "The End" on Sunday, so it took 6 weeks. Keep in mind, this was a rewrite, so it wasn't all new prose, but a major part of it was, plus I had to keep lots of details true to the story -- this is the final book in a planned 11 book series, so I was making notes like mad for details I need to layer into the previous books (5 of which are written).
So despite all the Churn (and oh, my I've had a lot), I did manage to write! Now it's off to review and edit a book before I submit it to my editor for consideration. The first of 6 I plan to submit.
But for now I think I'll relax and enjoy some holiday time and be ready to come back in January, raring to go. I think writing 4 books this year is enough.