Yup, I think it would be impossible to implement.
When a loan is taken out the lender can leave netural feedback on the loanee's profile stating that the member has a outstanding with them, once the loan is repaid they can change that to possitive trust feedback if the loan is repaid in full and on time or just delete the netural trust they left regarding the loan altogether.
Nobody is talking about buying trust here.
Just take a look at it I'm not familiar in this section of the forum at the moment but I will by time to time. Looks like a great idea so if that person ask for another loan would be great info to any potential borrower. Keep the good job guys.