Scene Capture 2D works in real time, as a character camera.
If you want to split the ENTIRE screen this way, then you don’t even need a “background” image, it will just be rendered by the character camera. Just to hide the furniture in the main camera - you need to make the character the Owner of all furniture actors, and set the “Owner No See” flag in the furniture meshes compinents.
Furniture - will be captured by an additional Scene Capture 2D (which is tied to the main camera).
In its settings, you need to select Primitive Render Mode - UseShowOnly List, and fill the “Snow Only Actors” array with furniture actors.
The second option (if I’m not mistaken) is to use Custom Depth and Post Process Material, but I’m not that strong in this topic.