Clever anit-theft switches

Battery in trunk with quick disconnect.

Certainly. I'm planning on an in-trunk disconnect with a push knob to kill it. You could use a rod and tube to make a sliding setup so you can push it off, but not turned back on. You'd have to open the trunk to power back up

There are a number of things you can do.

If you have a tach, use a switch to just ground the tach wire. It won't get spark on a "distributor" type (no cop)

If you have an electric pump, switch in the pump relay

There's a few circuits on an EFI vehicle the simplest of which is the pump relay. It bothers me, "around the net" when I hear about a tow rig / trailer / car has been "disappeared."

ANOTHER thing you can do, if you have a good memory, is to set up something like the pump relay switch so that if the ignition is activated with the security switch "off" IT WILL BLOW a critical fuse like the pump relay fuse. This will frustrate someone who has "time" to play with it.

If they show up with a wrecker/ roll back, you are screwed. You better be invested in some sort of tracking. There seems to be a number of GPS/ wireless systems. I have not kept up

If you are a family with a "group phone" deal set up one in the car for silence and so it can be tracked with an ap

If you are NEAR your car, say Mopar Nats, in a hotel, or at a big show, you can ALSO use various two-way radio services to alarm you. A switch in the car, dome etc........can trip the transmitter, and a "handheld" on your belt will sound the alarm. This won't track, but you will know something is up