you need a hidden kill switch somewhere in your rig. it many not keep them from steeling removable parts, but atleast they wont be able to hot wire and drive off you rig. Also, OffRoadOnly.com sells a magnetic relay cutout that opens the circuit after everytime the engine is shut off. They sell it through Quadratec.com in the electronics section.
And yes, full width axles would look kinda goofy unless you were runnin 3d9's or bigger with some massive fender choppin.