The first thing you need to install is a moat. Ensure it is both deep and wide enough to avoid an easy passing. Also ensure there are no trees within 50 feet as they can be used as an impromptu bridge. If you are dealing with persistant suitors you can put razorwire in the moat and then fill it with water. That should deter them.
If they are to persistant and make it past the moat then install several napalm cannons. These should have built in infrared and motion sensors. That should let them auto-target any interlopers who try to break in.
For a final line of defense have several wolverines. Their fierceness and tenacity should mop up any suitors who make it this far.
Pictures courtesy of Wikipedia.com