I tried to test some different modes and frankly nothing else comes to my mind anymore other than to put a heavy 40A relay to a main power line and attach a servo to it, so I could map it to one of taranis switches so in a case of malfunction or lost orientation I would be able to kill drone in the air or on the ground and stop props _immediately_.
Any other option I tried - a combination of 'land' mode with throttle cut off, an improved failsafe on remote switch off - none of that cuts power feed to props immediately, and quite often it leads to horrible results, like if in loiter mode drone suddenly gets to a GPS free zone or glitch, and starts something erratic, or flips over and tries to destroy everything around spinning props at full power ignoring remote commands to cut throttle input to zero.
I had only 3 incidents like that and I know now what it is, but it does not make my platform any safer.
What do you do for a physical kill switch? Do you have one built? If yes, how was it done?