[mr48chev]

Coil interrupt can be as simple as a hidden toggle switch in the feed from the switch to the coil. Electric fuel pump, same way. That is advisable for when you need to work on something with the key on but don't want the fuel pump running.

Battery shut off switch aka race car type but in the interior of the car where you can reach it and not be observed but still be out of sight.

I had a 63 GMC that I bought from my friend and couldn't keep running although it fired right up when you poured gas in the carb. It had a 35 gallon stainless tank in the bed. Sliding under the truck and tracing the fuel line quickly showed that someone had put in a manual tank selector switch at one time and the knob under the seat was turned to what amounted to "off" Turn the switch so gas flowed and it ran great. That would let a joy rider get about 100 yards at the most before it quit.

If I were inclined to have a pair of those electric exhaust cutouts on my rig for that added noise I'd leave them open when I parked at a hotel at night. If someone tries to start it it is going to make a lot of extra noise and draw a lot of attention.

Trouble is it isn't just the jump in it and hot wire it and drive off joy rider that may be the real problem now. It is the pro thieves with shopping lists at big events who may be using repo rigs to snag specific vehicles. Spot, back up, snag and go all in a few seconds. Best defense against that is park where they either can't get in park in a spot that it is extremely difficult to hook it and go.