Add custom content to custom layout Panels
You could place the images in a mini panel. Changes to the images would be done in the mini panel and would affect all nodes.

In Panels you can activate the Node view variant and create a panel (with a selection rule for the content type: Stuff). then use your Panel layout and place the mini panel in the column you want the images.

All nodes of the type stuff, should now use your layout with a mini panel holding your images. You can easily change the content of the mini panel and reuse it on other parts of your site.

Hope I understood your problem correct.