"Lock" HTML snippet in editor

I’ve got a unique issue I’m looking to a solution for.
I would like to have snippets of HTML in a page/post “Locked” (for lack of a better word) from being editable in the visual editor.

The goal is that, I as the developer, can add in custom HTML blocks in a user’s page that another user will not accidentally delete when editing their content in the visual editor.

Some options such as Visual Composer and Corner Stone have been considered. However, that feels a bit overkill for the task at hand.
The idea of using a short code to include the HTML snippets at load time has been tossed around as well. However, we still want the HTML to display in the visual editor.