I'm building an arcade cabinet and am re-using a monitor that is larger than the window for display so I need to use some aggressive overscan settings to make this work. I have everything working with /boot/config.txt, but every emulator is going back to fullscreen. Updating the cfg file for display_border in an emulator doesn't work well, as I need to use a somewhat large number and the width and height don't have the same border.

Ideally I'd like to keep the overscan settings in config.txt enforced for all of the emulators, but I'm open to anything. What can I do?