Adding an xClass-specific image to a form

With standard classification, it is pretty straightforward to add an image to a form that is only seen when viewing an item of that specific class.

But how to achieve this with xClassifications? I noticed that there is not even an image property type for xProperties.

Use case: We have a xClassification "Countersunk screws". For these, we need to define certain measurements according to DIN standards. To make it clearer what the measurements mean, it would be very useful to also provide a diagram, e.g. as below.

Any idea how to achieve this with xClassifications?

Thank you!