You can make it even more insecure: enable PDF-widget for lock-screen, write your password into a PDF file and save it into the connected folder. Now everyone can read it without trying to figure out which of the 80 keys are the correct one.
With my keyboard there are even 184 characters that can be entered via Squeekboard - a way too much work for local hackers. 
Edit:
In fact, for some reasons it’s not that bad idea - give a look into this thread.