I don’t have alot of experience. I see nothing wrong with your thought process on this. Seems like a good way to get the result you want.
As for room occupancy that’s another can of worms. I was just reading through this thread earlier today.
Has some good discussion on the topic and ideas. With additional links to other discussions on the same topic.
Just be aware a motion sensor typically uses heat moving to detect presence. So sit still and sensor says nobody is there. That’s why the big discussion on different ways to overcome this limitation.