Here is what you would need to do:
Supply some form of personally-identifying information such as an ID with your username written on a slip of paper. And then a selfie with your ID held next to your face.
The information will be held strictly confidential. If you would like to encrypt the message so as to not share this information with anyone who accesses your PMs on here, I will happily provide a public PGP key you can use to encrypt it.
If you default, I will not share your information unless we do not come to a repayment agreement. In the case that you do default, you can erase the debt by forfeiting your account to me. I would consider that repayment of the debt, as your account is likely valued around the same as the loan amount.