Featured image for exhibits

Is there currently any possibility to add a "featured image" to a certain exhibit in Exhibit Builder 3?
Currently, as I understand it, a "random" thumbnail is used if an item is present in the exhibit. But how would I go about marking an item (image) as THE featured image for an exhibit?

The thumbnail Exhibit Builder selects is the first item attached in the exhibit. So, creating a "front page" for the exhibit that includes the item you want to use as the thumbnail would be an easy way of controlling what thumbnail Omeka will use for it.