> A battery shut off switch would be the easiest, and fool proof.
> 
true, but who wants to reset the dang clock every time you get in to
go anywhere?
I opted for a push-pull aircraft circuit breaker inline for both the
starter solenoid and fuel pump, both unlabelled and on the same panel
with eight other breakers under/behind the driver's seat. reach back,
pull 'em out, no more starter or fuel.