Managing & reporting Loans or Microloans to org from individuals?
You can add Custom Contribution fields (on a per 'Contribution Type' if necessary) hence if you need fields that show Interest Rate etc you can do this via the UI.

I am unclear if you need the user_unique_id since the civi 'internal id' might do the required. Ditto for 'creation date' etc as these might be data that core civicrm handles anyway.