Er... back on topic, it sounds like what you want is a special model that's similar to another capship model, but with a debris LOD that's more or less a whole capship, maybe with a hole in it or something to make it clear that that thing's not gonna be fighting again any time soon.
In other words, can be done infinitely better and simpler with proper modding than via coding. Maybe something to make debris destroyable (last I checked starjunk had infinite HP, since there is no hitpoint level set for destroyed vessels) should be added, but beyond that- well, you'd really want a more dead-looking "derelict" model than just a slightly scorched version of the working ship anyway.
And what are you talking about a 10% limit on capships? I've killed dozens of them, and I'm pretty sure there wasn't anything big helping me...