Toggling does require you to keep track of states. Would that really help you so much ?
My setup is reasonably simple, and uses commands to change the modes of selected tracks, ALL tracks or use a global override. Perhaps it is of use to you, or can serve as an idea to develop your own setup. It uses the block of keys INSERT, HOME, END, PAGE UP and PAGE DOWN.
Selected tracks
INSERT - Touch
HOME - Read
PAGE UP - Latch
END - Preview Latch
PAGE DOWN - Write (the most destructive mode)
ALT+key = all tracks change to the mode
For two modes, Latch and Latch Preview, I have global override keys setup, but I hardly ever use this. I might remove those binds.
This works extremely well for me. I use this all day, mixing dialogue for film and TV. Would this be useful for your workflow ?