I see trying to explore alternatives here, am I mistaken thinking the 2d UI would be great to work with images like backgrounds?
The question is how do then get the UI to show up behind objects in the scene? Its kind of defeating the original point of UI but methinks doing that will give me greater control over dimensions, aspect ratio and so on?
That’s a good question, thinking how to approach that. One way is to use two cameras, a UI camera that is rendering first and your normal camera that is rendering second without clearing the color buffer.
That way your UI camera will render the background at the start of the frame, and then your main game camera will render everything on top.