you could try the Slocum ploy - tacks on the deck. Once an intruder stepped on deck on one, you can be sure that even if you were awake you'd hear it.

Or, I have an idera for certain areas of the world: how about a voodoo doll by the compainway and some other demonic or witchcraft type object that
means 'don't mess with me or....!'.

Or, how about hanging a SKELETON from the boom!!!

Jerry