Signing a bitcoin address will be difficult for me as I'm not using my own for a very long time. Mostly they are from either exchange or other sites that don't provide control over addresses. Although there are more ways to prove the ownership of this account and won't be a difficult task for me.
You know though that signing a staked address is the best way to verify the ownership.
Sorry to say this but a member like you sounds quite impossible not to have a wallet that he can sign at any moment.
On the other hand, why don't you ask from TF and help to his test? You won't need any kind of Collateral as he say..
