I like the last idea. You could probably make an argument that it would be more efficacious as a deterrent (assuming that is part of your end game) if it is clearly visible.
Maybe add a sign that says, "You are on camera. You can smile...or not, I do not give a %&*$."
If I am honest, I am so paranoid I would probably have fifteen of these stupid things inside and out if I was not aware of my neurosis.
You need to figure out how to use a battery strapped to this thing to get an idea of how long it would run before it had to be changed. Make it so.
I think a 10000mah battery will run it for a couple days.