You don’t need a faraday cage if you suspect he gets the moves from outside. Just put a 20 minute delay to the video feed and don’t allow random people in the room.

With no visible or audible audience either.

Well, a vibrating device can be anally inserted. So maybe the Faraday cage is enough, unless we will be doing cavity searches.

this is really the only way (maybe not naked, but change into preapproved uniforms)

You could still run a chess engine offline on a decently powerful phone that would beat high rated players afaik.