Again, THANKS all! I'll go peruse those links here in a minute.

Those who are offering various mechanical or driver-applied vacuum scenarios - I clearly haven't communicated the issue well. The safety guys have to be able to walk up to the back of the truck and flip the battery (main power) switch and have that result in an engine shutdown. If the driver is incapacitated any driver-applied solution no longer applies. Anything less than that isn't safe and won't pass the tech inspection. One possible solution would be a solenoid that would press the linkage shut-off lever whenever power is removed but I suspect there's too much room for system failure to pass tech - but maybe not. It IS a possibility.

Here's a pic of the main power switch, just to be sure we're all on the same page. Nope - it won't let me repost the pic as it's already in my build thread (wish they'd change that). Basically, it's a battery main power switch mounted in the right rear corner of the truck.

Dan