mombo,
When I installed my auxiliary fuel pump I put it in the fuel line along the frame. At the same time, I installed an inexpensive ball valve to shut off the fuel. I drilled a hole in the valve handle and attached a push-pull cable, such as you find on lawn mower throttles. I routed the cable to a location near the driver's door at the bottom of the body. It's not visible unless you squat down.
Pulling that cable closes the valve. The truck will move about 50 feet and then shut off with the valve closed. It also won't start easily after it dies. Trust me, I know.
Good, cheap security.
Loren