Hi zaroth,
This makes sense, and we are already doing some of that.
In the loan application form that borrowers see, the 5% fee to Zidisha and the interest offered to lenders is in fact combined. Borrowers choose any combined rate from 5% up to a maximum of 30%, with a text description indicating that the first 5% of this is paid to Zidisha and the rest is paid to lenders.
The loan application page also indicates the registration fee, as a cost separate from the combined interest / fee rate that the borrower selects.
We separate the service fee from the lender interest in the loan applications that are displayed to lenders, because the intent is to indicate the maximum interest that they can expect to receive from each loan proposal.