"If such individuals exist, they represent a small minority and have not been identified yet." -> You should talk to them then.
A good blind study would be a EMF isolated room (shielded mesh, etc), a assistant you don't see (no visual or accustic cue at all) and a procedure you can repeat.
You go out, the assitant sets up the experiment (which is recorded, somehow EMF free), either activates an active EMF (perhaps constant file transfer, radio antenna etc.), the person leaves the room (the source is hidden), you enter, you wait x minutes (probably more than one), you either say yes or no and leave.
If you are clearly above random and you can show this result, you would be a good candidate for proper research.
Your assumption that you proof your EMF sensibility by recording the messurement after is way to unprecise. You might hold your EMF device wrong, ignore values, might have some visual or accustic cues etc.
What device do you use to messure EMF? What range? 5G has a broad spectrum, your sector antennas might send while you messure because someone is doing something close by etc.