Put a hidden kill switch in it connected to the main relay so it will shut off the fuel system. Also it would be good to kill the start circuit so they can't sit and crank it till the battery is dead.and a kill switch maybe.
An alarm is also of course a good way to go. I have a Clifford alarm in my '91 hatchback. I still need to wire up a kill switch.
That really sux. Glad the A-Holes didn't get your ride.