[Jaydee]

Year ago I had a system that filled the car with smoke when the alarm was on. All it was is a 1 foot length of phone wire inside a Bakelite tube with holes drilled in it, and a hidden switch. If the switch was on and the ignition was bypassed it would short out the wire and instantly fill the car with acrid plastic smoke. It would only drain 5 or so amps.
I might hook that to a seat pressure switch.
JD