Custom and Mandatory fields on Notes in Documents

What is the challenge?

I need to deploy data classification and document metadata onto notes in the documentation space.
I can create custom fields, but I cannot make them mandatory at the time of creation, or ensure they are updated when documents are updated (eg: "last modified by" and "last modification date")

What is the impact?

I will not be allowed to keep using Aha documents if I cannot implement our data classification policies.

Describe your idea

I have a need for some custom fields on documents that are created to be mandatory (ie: must be populated).

An example of this is a field that captures the data classification of the document (ie: Public, In-Confidence, Secret etc..)

Is there a way to make a custom field on a document something that MUST be populated, like it can be for custom fields on other record types?