I've made another workflow based on what @DGW mentioned. This works in Offline Notebooks without Internet connection, and doesn't require any additional input of S-Codes or User IDs.
https://workflow.is/workflows/87dbe36dd5614c448c28bf34c736c326
FWIW, I've also used Workflow to attach attachments to my Evernote on my iPhone (since that feature is totally absent from iOS), so I think it's well worth understanding how to use such a powerful tool.