I'm not even sure what is possible using the API for Content Migrations. Can you create new courses and import content into them in one process? I have found a Python and Windows PowerShell script, online, that look like they are creating courses and then importing content (various migration types) from other LMS sources. They use an Access Token for authentication, as do SIS Imports. I know you can do this via the UI, but I am looking to do several courses at a time.