.........cut off switch...........

4 pole switch with a jumper wire. You need to run a wire all the way back to the battery.

Also, might want to think about a continuous duty solenoid to kill the alt. wire dead when you cut power.

On my phone now, can post pics/more details later if needed.

X2 on the continuous duty solenoid
Everything forward of the trunk battery is dead when you hit the kill switch.
I carry a jumper in the trunk I can bolt in to get home if the continuous duty solenoid ever fails.