If i had access to your PM and account generally, which the moderators do here by the way. Then they know everything, including the btc address you sent on and probably the signature you used for your BTC address.
I'm absolutely no expert but surely sending a Qora address to Qora. Then he takes the list and puts it next to the BTC donations. Then give everyone a week to see that list, which gives people a chance to say if someone has sent a false address. Then Qora sends out.
Your idea about the list is not bad... however... the
signing a message (Qora address) with the sending BTC address route is very safe and probably the best way to go... review how signing messages with your BTC address works and it will become clear very quickly.
Edit: Will not work for those that sent BTC from exchanges though.
So you make a Qora address and use that to sign the same BTC address you sent the stake bitcoin?
The on the PM post the BTC address, signature and qora address?.....seems fool proof.