You could use a hidden script - within the editor click in menu on file. Further you could use include-variables to load your script from an external file - but you need to make sure that the reload-user had access to these path and the normal-user haven't.
Assuming you will look to distribute your document via Qlik Sense Server when ready to publish to production environment then you can lock down access to the document so only certain users can access it and whether they can administrate the document or just view it in Server.
