That's the first thing I tried. Unfortunately, custom LOS settings kill the framerate after the application runs for a minute or two. I have no idea why this occurs, but I know my machine isn't the only one that experiences this issue. Here's the original .cap running with custom LOS:
It'll run at a healthy 70+ fps for about half a minute, then start dropping into the 30s, and finally plateau at below 10 fps. This may not be an issue on fast machines, but this is meant to be a simple, 16-bit-style game. If my machine, which can just barely run Orange Box, can't handle it, a lot of my target audience won't be able to either.
That's why I need to figure out how to bypass the need for custom LOS. I was hoping there's a way to ignore an entire layer, or something to that effect.