Specify Region to be Hidden

Responding to our Editors, I have included a Perch region which will not be displayed, using CSS to set the region to display:none;'

The Editors want the facility where they can add notes and acknowledgements and possible alternative descriptions to a published story so they can be reminded if they have to revisit the story at a later date to make changes. They don't want this content to be read by viewers, hence my CSS to keep it hidden.

However, if a viewer looks at the Source for a page with a hidden content region, then this Hidden content is visible.

So, is there a Perch function that can be applied to a region such that the content shows up when editing in Perch but never gets sent to the browser when the reader looks at the page?

(I've looked at the thread 'hidden content' but this doesn't cover what I'm looking for)