Hello @hanland
For that you can use onSubmit event with your logic.
You can hide File and View tabs with corresponding parameters:
layout.toolbar.file: Customization - White label | ONLYOFFICElayout.toolbar.view: Customization - White label | ONLYOFFICE
Please pay attention to this note on the page about extended customization:
On this page you will find the customization parameters available only for the extended white label license of ONLYOFFICE Docs Developer.