That's a good idea. Maybe a desk lamp that gets turned on? Think about how you dress as well. Clothing is an excellent signaler. Consider rearranging the furniture to create a barrier between your desk and the rest of the room. Those folding standup room dividers are like $100 on Amazon in a variety of styles and you can hide it in the closet after hours if you are short on room.
Yah, that's what we wound up doing spontaneously today when something spilled in the kitchen this morning. We have a kitchen island on wheels, I wound up rolling it out of the kitchen out of the way and wound up just continuing on over and creating a side wing/short wall next to my seat and keyboard tray. So far so good.
