Can Rhino extract only exterior surfaces of the model ignoring all of the inside geometry?

I need to find out the way to lighten model as much as possible ans have only outer faces of it. When I try to achieve it through boolean, it makes a negative copy of the volume with all of the inner geometry. Is there a way to make something like a plaster mold, so Rhino would read a model as a whole solid or ignore insides?

What about the windows and doors? You still want those features?

I need every surface visible from outside, i.e. front side of exterior door (not the inner side)

Hi, were you able to solve it? If yes, could you please share the solution with me too?

Have you tried BooleanUnion? At least if all the geometries are touching, you get a single Brep.