I have a combo box next to the back door. Its not hidden. If someone wants to get in my house, they're just going to break a window elsewhere on the house instead of using a crowbar and sledge on the lockbox.

You don't have to go to elaborate measures, just enough effort to make it so they'll find some other way in, or move on. Typical American houses built in the last 20 years are defensive nightmares so chances are they'll find another way in without much effort.

Everyone's situation is different of course. But you have to think about the most likely course of action. Don't be too smart for your own good.