If your truck has keyless entry/start how are you expecting someone will steal your truck?

Are you concerned about someone cloning the key / sophisticated attack?
In that case you don't need a remote activated kill switch. Sounds over complicated and subject to a similar type of attack. I think you want a physical switch hidden in the truck that is cutting a wire like the starter signal or fuel pump.

Complicated electronics are not a major factor here, there is still a sequence of events like a starter that needs to be activated.

 

Yes, if you have keyless start, always keep the fob in your pocket. If you put the truck in Park and get out with the engine still running, it can't be put in gear.

In regard to your kill switch idea, seems to me that in the very unlikely event that you find yourself being carjacked, it's going to be a surprise, you're unlikely to remember your kill switch at that moment, and if you use it you're really going to **** off the carjacker who is probably armed. That's not smart. I definitely wouldn't start messing with the wiring in my truck to try to prevent something that's about as likely as getting hit by lightning.

 

Those steering wheel locks are useless. Thieves just take about 15 seconds and a hacksaw to saw through the steering wheel and remove it. For the more civilized thief that owns a lockpick set, well, just check out LockPickingLawyer on YT. You'll see how, "effective", those locks are.

 

Nothing is useless, except "knowledge" from Youtube. Most auto thieves aren't carrying hacksaws and aren't prepared to pick locks. At least a third of them rely on morons leaving their doors unlocked and/or keys in the vehicle. Anything that presents an extra challenge or delay sends most thieves looking for another victim. That's according to cops, not Youtube amateurs.