OMG, this is amazing, I must admit that I had my doubts from the title, but this is so cool.

As for ways to add it into the cosmology... well I had an idea. And this probably proves that I am a disturbed person. If you can insert one plane of flesh, why couldn't you create two. And let's say one of those planes was dead, or more approperatly undead. Place one right next to the Positive Energy Plane, and the other next to the Negative Energy Plane. Of course the undead one might have some spots still alive and fighting to hold on, sort of like the necrotic patches in the living one. So it would basically be an opposed plane.

In fact, if you will allow it Zeta Kai, I would like to do that with the cosmology for the campaign setting I am currently creating. Full credit would go to you of course. Will you allow it?