Have you tried teaching without any textbook at all? Because that's how it worked during my CS education in Germany. All course content was written up in the lecture notes provided on the course homepage, variously a neatly-formatted LaTeX document or a scan of the instructor's literal handwritten notes. Sometimes there were also optional recommendations for further reading, but I recall one memorable case where a student asked the prof to recommend a textbook, who wasn't able to give an answer on the spot because his course wasn't designed around any particular book.

If you think that writing down everything you want to teach sounds like a lot of work, well, that's how you benefit from relying on a textbook to supply the content for you instead.

EDIT: Perhaps I should've read TFA first, considering that it describes a textbook grown out of the author's lecture notes for a course taught without textbook.