I think the most reliable and easiest way (probably cheaper in the long run too) is to clip on ruggedised standard test equipment. One easy way an oscilloscope, or a Counter/Timer with A/B triggering. Instead of fragile scope probes, make up some sturdy croc-clip leads. Will take some skill at first to set up and use triggering. Many electronic engineers don't know how to trigger a scope, so don't feel bad if it seems daunting. Many scopes have stored setting recall for unskilled users.
TENMA|72-6800|OSCILLOSCOPE, 20MHZ | Farnell United Kingdom
I presume you wish to deploy this in front of the competitor to help you judge if they're cheating. Problem I can see is that they will get round this next time by using a secret hidden 'bypass switch' to bypass the illegal delay timer. I guess you could get round that by doing always doing the test secretly.
Trouble is, it might all get like miltary intelligence, decrypting enemy messages where you learn definately something is going on, but you can't act on the infomation. This problem was in WW2, it bugged the British who decrypted nearly all the Nazi traffic, but couldn't do much with the information because the Axis would suss it and then strengthen their codes! Why I say this, is because if you do catch someone using technology with your technology, at some point you might to need to 'show your hand', if the person denies having technology. So you'll probably need to think on your feet.
Maybe you can develop the rapport and trust you've got with the competitors perhaps suspected of using illegal technology, and get them to help you create a solution with them that will ensure it's a level playing feild for all. Bit like performance enhancing drugs in sport innit!