bankruptcy remote entities are typically single purpose LLCs with special provisions limiting the operations of the LLC and limiting the ability of the LLC to file bankruptcy; I would recommend a separate LLC for each loan, which in turn can be controlled by your master servicer.
This may be a good case study for you to read so that you have a better sense of how (and how not) to establish your SPE's for the crowd funding aspects to individual borrowers. Good luck to you.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained.
You will want to work with several attorneys in accomplishing your objectives. Both a bankruptcy and a securities attorney each of whom can help you establish the bankruptcy remote SPE. Someone with tax experience to talk about tax efficiency in the overall structure. Finally, you will want to hire a good banking lawyer to work out contractual issues with the third party bank.
You not only need a securities and tax attorney to work with you, but also those involved with banking given that you'll be using a "private bank" to issue and underwrite loans. The regulations in that area alone will require able counsel. But if you're looking to provide the payments to the investors on a regular basis, why not simply use swaps?
The foregoing is not legal advice nor is it in any manner whatsoever meant to create or impute an attorney/client relationship.