I got a 1987 Ranger not even a week ago, and I'm suspicious that someone in my neighborhood might be scoping it out.
Last year, I owned a Honda Civic which was stolen from right in front of my house, so I'm pretty paranoid about losing my new truck. Besides buying anti-theft devices, is there anything I could do that would make it inoperable until I was ready to drive it again?

 

Visual deterrents, like The Club can send amateur thieves to another car, but The Club is easy to remove so not an anti-theft device.

Also Cable thru a rear wheel around leaf spring

Fake flashing alarm LED :)



A timed fuel or spark cut off is best, but it won't stop the break in and key cylinder damage.
The timed part means thief can start engine, and drive car away but fuel or spark is cut off after 30 seconds or so.
Thief is now stuck out on a public street somewhere with a stalled vehicle, not hidden away, so they will not try to find the problem they will walk/run away.

You would set this up as automatic enable at power on, so no switch to remember to turn on/off.
You would have to push a hidden button before the 30 seconds were up or engine would stall, but pushing the button would get it running again.