This still isn't 100% theft proof(could be towed away), but thieves are lazy and aren't going to take the time to defeat all of them, they will move onto an easier target. This is all you really need to do, is to make yours harder to steel then the next guys.
I had a truck stolen in 1998... A 1973 Chevy Custom Deluxe Stepside. Black on black, with the factory rust option, more primer than paint, a rotten wood bed floor, and the classic Chevy hood crease (anyone who had owned one knows what I am talking about). It had a removable steering wheel, removable radio, El Cheapo Realistic speakers mounted where the shoulder strap (optional) mount holes were located, kill switch for the coil, manual throw switch for the battery, wheel locks, and personalized plates... "73 SIDE".
It was hauled off on a flatbed in the middle of the night, right out of the barracks parking lot on Ft Eustis. <img src="/forums/images/graemlins/zombie.gif" alt="" /> The truck was recovered 2 weeks later, and I sold it to the junkyard for $50.
Why was it stolen?
I transplanted the engine from a 1969 Chevelle SS 396, punched it to 408, had a roller set, Gear Drive timing set, 11:1 compression, 1200 CFM carb, Tri-Y headers, Torker I intake, MSD Ignition, Muncie Rockcrusher 4-spd tranny, 3.73:1 posi 12-bolt, 1100 cca battery, and ran sub-10's in the 1/4.
Why did I sell it for $50?
When recovered, it had no battery, engine, seat, axle, tranny, dash, fuel system, ignition system, or rims... Stripped out, and sitting on blocks. The only parts recovered were the frame and rusty body, everything else was gone. It was found in the woods somewhere in Gloucester County, Va.
If they want it bad enough... It's gone in 60 seconds. <img src="/forums/images/graemlins/angry.gif" alt="" />