How can I tell if a mesh is visible and not occluded in a render with an orthographic camera using python

Question

I have an imported model with a complex set of parts, some of which are internal - i.e.: always occluded by other parts - think of an inside lining in a sofa.

Is it possible somehow to tell programmatically if some parts are visible in an orthographic view?

This is not about testing if they are in the camera's field of view - it is about checking if they are occluded by other parts.

I am thinking of color-coding them, rendering and checking if the color is visible, but I want to know if there's another way before going down this path.