Another option is a heavy duty relay that's energized by a small toggle switch when you want to run the truck. The downside is the relay would need to be heavy duty enough to stay energized while driving, and the control switch would need to always be energized (and fused.) You could put the toggle switch in a concealed location under the dash and the relay on the frame near the battery.
Or if you aren't too worried about battery discharge, and just want added security, you could intercept the power feed to the ignition switch with a concealed switch. It would still crank from the stomp starter, but wouldn't start or run.
