Here's a project for someone -- we need to modify the build system so that the PDF version of the book comes out in 7" x 9.25" page format (the same as most computer books, such as the Python Cookbook). This way we can verify whether 80 columns is OK for our code formatting before we get a lot of code invested. Also, we can start debugging issues with the print version early.
This will require learning more about Latex and how Sphinx produces it. If Sphinx can't be told directly to output in the desired format, it may require a Python script to post-process the Sphinx output.