Void Fill with Component - does this exist?

Is there an extension that can create a component (recognized by SketchUp as a solid) to fill a void - such as a wall cavity?

I’ve done an (admittedly brief) search of the Extension Warehouse and Sketchucation for such a thing, with no success.

Use Case:

I’m designing/modeling a Tiny Home on Wheels in SU and will likely begin construction by mid-summer. I’ve (slowly) managed to assign weights (by volume) for the building materials I’m going to use. One material I’ve NOT yet modeled is my insulation - primarily because I’ve just recognized that I’m going to fill empty spaces and haven’t (yet) bothered to fill those empty spaces with components representing the insulation.

While creating these components will be (relatively) easy when the edges are aligned with the models axes and the shape is a simple box, stuff gets harder when I want to do this off axis or for a more complex shape.

What I envision is an extension where you select a point in an otherwise empty space in the model and the extension will find the boundaries of the empty space and create a component to fill it.

If such an extension doesn’t exist, I’ll likely do a better job defining it’s function in a post to the Commercial/Collaborative (or possibly Developer) categories.