Creating a custom Interior designer / engine within UE4

Hi all.

I’ve been looking at the realistic rendering videos that uses UE4 to create photo-like images and real-time rendering. With Ray-tracing coming up I want to see if I can create an “Application” with one level, with editor-like functionality and tools. Shortly put, I want to create an engine which inherits functionality from UE4, basically an engine within an engine. Is this a farfetched idea?

I can’t really find any documentation or answers regarding this topic.
All feedback is appriciated.

Cheers!