Something to consider is letting the lenders purchase the ASICs themselves and have them mine however much BTC + interest they would have obtained. After they're done they can send you the ASICs for free (you pay shipping).
But why would anyone do this, when they can buy the ASICs, and mine with them till they are far above the payback rate?
Agreed. Plus, as I mentioned before, there is no security for the borrower. There is also the lose of revenue during shipment to consider.