These guys are amateurs. You don't try every fricking car door and then case a bike...they're being opportunistic. If the bike was their priority they would even bother with the small stuff....it'd be like walking around Costco stuffing your pockets full of candy and then trying to steal a flat screen TV...it just doesn't work.
I mean...that's what I would do, were I so inclined....ish.
Nobody was suggesting they were determined professional thieves (if you can call thieving scum professional ) but if scum is prowling your neighbourhood upto no good Kwacky is right to be concerned and looking to proactively protect his property rather than deal with the consequences afterwards imo.
The more you can put these wankers off or slow them down the more likely they are to look elsewhere which is hopefully some hard as nails, pyschotic, light sleeping head the ball who has a desire to educate these scum in more acceptable moral behaviour
If your targeted by a professional they will be taking your bike. If you make it too difficult it could become aggravated theft which is not worth it imo. You can only take this so far and then it becomes questionable if worthwhile.
That kinda stuff always puzzles me....theft/crime in my old neighbourhood was virtually zero...but 4 blocks away it's rampant. - Yet that's where there's nothing worth stealing!!
Clearly you've already had a lot of suggestions mate. I can't help anymore! Hope you find what is best for you and your garden to protect your property. Or you move to the states and f%&?ing shoot the bastards that go near your property!