Custom state label in plugin

I've been searching for an answer to this and am probably dancing around the correct terminology.. I have a plugin I've built that exposes a custom motion sensor device as part of its functionality. The device is defined in devices.xml as a "sensor" and I've added some custom properties and states to it. I can update everything, changes are reflected in the UI, etc. and I'm updated the state image with MotionSensor/MotionSensorTriggered. Next to the state image I see either on or off, and I'm looking to change that (not just for motion, but I have another device defined that is a contact sensor so I'd like to have the text be opened/closed in that case).

Unfortunately, you can't change that with a standard Indigo type. There are some things you can do, like a lock symbol and locked/unlocked status. But Indigo doesn't currently have a defined "Door" or "Window" type that will show open/closed.

You would have to make it a custom type and then you can supply anything you want for that field.