I of my friends have hidden a old phone wire to charger and put a pay as you go card in and set it to meeting ( no ring tone ). If his goes walk about he can give the police the number so it can be track throw the phone. If the car tracker is turned off this is a back up.
I hope this may help and let you sleep better.
Regards
Richard
PaG sims can expire - also using a phone with GPS and a "find my phone" app would be a lot faster and accurate than relying on triangulation through the GSM networks.
My disco has an airbag in the steering wheel, not difficult to wire that into the ignition with a hidden kill switch....
Until that one time you jump in and forget about the kill switch in a rush. Any damaging related mods with kill switches are just a hazard waiting to happen. Preventative starting kill switches make sense (fuel lines, battery, second immobiliser, etc.) - but not any which could hurt you or your landy.