I don't think the OP's rates are excessive after all he is not accepting collateral and is no different to a payday lender who will inevitably get bitten a few times so needs to offset that with higher rates.

What bemuses me is why anyone would want/need to borrow 0.005 BTC that only around £1.33/$2.24 what are people going to do with that tiny amount of funds ?

Anyway good luck to OP