Laptop enc. auto-dismount

I'm having to deal with a situation with a risk of possible adversary snatching the laptop while encrypted files are mounted. I'm trying to find a way to do automatic dismount. I was thinking of applying something like

1. Script that scans for mobile phone's WLAN station signal and then dismounts if the station is either turned off when the signal fades over distance.

2. Script that scans for a bluetooth device I've in my pocket: similar like the last one

3. USB-device; removing it runs the dismount script.

Any ideas and instructions would be most appreciated. Platform can be either windows or linux.

 

A locked door or two prior to your main laptop work area would give you enough time to power down.