Actually, the negative layer panel feature won't have anything to do with this. It'll be useful for pure 2.5D games, but my game is still set in a completely 3D world except everything is 2D planes (or sprites) with the real geometry hidden.

The only visible real 3D will be the characters; however I'm even thinking about making them 2D. I'd need to render out a bunch of frames, but it would free up the poly budget. I haven't thought that one through, though because it would take A LOT of frames. I'd need my standard 8 directions for both walking and running, the in-betweens when turning, idles, special case renders for moody, Noirish lighting, the same frames for different camera angles, etc. This would lead to another potential problem.... Can stencil shadows cast from an invisible model? I know they won't work if the model is transparent. I'd want to use a low poly version of the model used for the 2D sprites to cast shadows with. If this is impossible then I guess I'm screwed. I want to focus on this shadow problem first, though.

Why do I have to be so unorhtodox?