Well, I don't recall editing anything beyond that chunk of code, so I'd assume it has to be something in here that makes it work:
< code>
The majority of those limits are probably bumped way too high, which I'd imagine causes the memory leak. 
#define MAX_FS_CROSSSECTIONS 64Could that be it? The rest of it isn't really geometry related and so shouldn't affect ships like the HTL Fenris or Orion. I'd imagine TBP would love you if you could bump FILES_IN_VP a bit too, though I don't know the consequences of doing that.
EDIT: Also, the memory leak isn't caused by any of the bumps, just exacerbated by them. You don't notice a leak for the length of time people use modelview when you're using up memory by the Kbyte, if that fast, but when the limits are set sky-high then things get more problematic. Of course, as a coder, you know this. I suspect the leak has to do with (re)drawing the render window, since the leak becomes a problem fastest when I'm dragginig a ship around to edit it. The other time it ginds to a halt is when I'm changing something that affects the render state (like moving a subsystem point, or switching between display modes) so it might be related. Of course, there's a myriad of things going on back there that I can't see and don't follow well enough to really know.
EDIT2: You can probably solve the glow problem, at least temporarily, by reading in everything after the last retail data chunk to a buffer and then writing that buffer on save after you've written the POF, before you close the file. That'd be at least a stop-gap solution to the problem, if you don't want to impliment another drawing option for the window.