[bigiain]

So the not-dumb ones probably also know of the existence of things like this: http://www.amazon.com/Linear-Garage-Opener-Receiver-Remote/d...

If you need more than around 200feet of range, a coathanger as an antenna at each end could probably triple that range, a couple of coathangers fashioned into a pair of 310MHz yagis could likely get you several miles range.

All for less than a Raspberry Pi camera.

Even if you, as a "smart guy" were also a bad guy, would you _really_ consider doing things "the hard way"?

The "bad guys" already know reliable ways of long-distance remotely triggering IEDs: https://www.google.com.au/search?q=IED+trigger&num=100&tbm=i...

They're using those cell phone we all threw out 10 years ago. (I think I see a dozen or more of my old Nokia 8210 there...)