I am liking the anonymous DA letter idea - sent to the local BOE.
Include some personal hints e.g. mentioning something specific about the elders so the elders will all feel obliged to read the letter.
I can see this would be a particularly insidious and destructive weapon.
Because they would feel obliged to read the letter to look for clues, the elders would unwittingly be exposing themselves to the reality of the WTS. Some may even be prompted to go online and look for themselves.
It would also continually play on their minds because they would perceive there was an apostate in their midst, but not know who this was, and this would create uncertainty and also keep the contents of the letter in their minds.
They would be trying to work out who in the congregation sent it. They will be looking at everyone suspiciously.
It would be subtle. Very subtle.
I like this idea a lot.