Site Publisher Template field thumbnail End User UI

In any large site Publisher template, it can become hard for the end user to understand how the “second section sub title” field will look like on the final page (and also know where it will show up).

This is why I would like to possibilities to add a preview image to individual field, not a mandatory field. The image would only show up if it was provided. The thumbnail would greatly help the user understand where the actual field will show up on his finish site.