A kill switch is a really good deterrent. I wired in a hidden pushbutton ON-ON switch that when pushed out connects the ignition to the horn and when pushed in connects the ignition to the starter relay. If someone is trying to hot-wire my truck they will be letting me know smile also, a battery cutout switch is great but neither do much for you if someone is simply going to drag it away.

1959 Chevy Apache 3200 stepside
Forged SBC 383 Stroker with TBS 192 Supercharger
Tremec TKX 5 Speed transmission
Mosier GM 12 Bolt rear end
18" Detroit Steel D-Town Wheels

1947 Chevy 3600
No mods, all original