Can you link to the paper? Happy to read it. My thoughts/plan in general though: basically do what facebook credits did. Get licensed as a money transmitter, collect info on all users to comply with AML and know your customer laws. It's a pain, and expensive but doable and there is precedent for it (Paypal blazed this trail as well). Then there will be a PR battle where you win hearts and minds by highlighting the benefit to small business owners.