Technically this works, but I would recommend another addon called "Overscan Render" after trying both the other allows you to easily revert to your original camera settings, uses a percentage slider rather than pixels, and automatically protects the aspect reatio and size of your cameras background images when you add overscan making it easier to use.
Render Overscan
Technically this works, but I would recommend another addon called "Overscan Render" after trying both the other allows you to easily revert to your original camera settings, uses a percentage slider rather than pixels, and automatically protects the aspect reatio and size of your cameras background images when you add overscan making it easier to use.