PC - yes, it's particularly good info. Your idea costs you money. You may be seen - and the JWs will realise the fliers are placed by someone outside the Org (I'm not trying to rubbish your idea, I'm just weighing up, what I believe, is the better option)
Bluetooth is free. There are a lot of board members who still attend meetings. Bluetooth has a limited range. JWs will have their mobile phones on (on silent) during meetings. If they receive a Bluetooth message, they will *know* it came from a member of congregation (but they won't know who) so they WILL read/see it and it will be private (they won't need to worry about anyone else seeing they have it).