> How do you guys keep it manageable?
We probably don't: like most mathematicians, we live and breathe LaTeX!
[Here](http://math.ucr.edu/home/baez/control.pdf) is a paper Jason Erbele and I wrote with lots of diagrams in it, sort of similar to what you might want, and [here](http://math.ucr.edu/home/baez/control.tex) is the underlying LaTeX file, with lots of TikZ diagrams in it.
It seems stressful at first, but after a while one gets used to it, since one is mostly reusing and adapting the same bits of code over and over. If we could afford to pay someone to create a better system, we probably would. Instead we listen to lots of music while working.