I followed a tutorial on turning off the screen for the shutdown command and that worked with the shutdown command, but not by using the menu to shutdown. I ended up making a modified version of rpi-display-backlight.service that removes the conditional and runs the command to shut off the display and that worked great for the menu only, so I ended up just implementing both methods and it's working good. I also figured out how to disable the screen blanking because it was getting a bit annoying. It was really as simple as installing xscreensaver and disabling it through the menu, so turning it back on through the UI is pretty easy.

I did a little bit of research and it looks like I will probably end up making my keypad driver into an lxpanel plugin so that I can display if the 2nd or Alpha keys are pressed. For the battery level, I think the best approach is to look at interfacing an existing battery lxpanel plugin with my code that reads the voltage level so that it will display on on the menu bar.