If you want your car to be totally theft proof then encase it in concrete and drop it in the sea. This about putting obstacles in some scumbag's way. Hopefully your alarm is screaming, they now have the bonnet up and are trying to connect wires in the dark in a public place.
Put a fuel cut off on, an alarm, steering lock, bad ass dog, hasp and staple on the bonnet (that's doable) etc. OK so they get in, can't start it so they just steal all your stuff instead. Anything you can do is a plus I think. I have put a padlock on my wheel carrier so you can't get the tailgate up and today fitted a full cargo barrier. Not they'll have to smash the windows and lean in. But they won't get the drawers open.
It's a shame we have to do this, but whilst ever there is poverty, greed and drug use, we'll have to take precautions.
My immobilizer doesn't link to the solenoid, but I have no idea what it does to link to. It won't turn over and if you keep trying it sets the alarm off.