We're all aware of the big red steering wheel locks out there. Designed to lock your steering wheel and prevent theft. I am guilty of running one on my old Jeep. Even though I do know that they're easy to defeat and only deter opportunistic theft.
With the TJ, I went to a RFID based secondary starting system. Not Sentry Key, but my own home build system. I'll cover it in a future post.
For the quick security, I went about as simple as you can. I put a padlock on my Jeep. It's really quite simple. I went with a Brinks shackle style lock. I put the drivers side seat forward and leaning against the steering wheel. Once set in that position, I drilled the base with a hole big enough for the lock. It's down near the floor of the Jeep, and behind the little spring plate cover. Once the lock is in place, it's impossible to move the seat back. I doubt bolt cutters could get onto the shackle, and without a torch or cut off tool, the lock is staying put.
The would be thief can't put the seat back, and if you can't sit in the drivers seat, you really can't drive away.