OK, I just FINALLY read this whole thing.
I'm not quite sure if this is what is being suggested here, but it is possible to make it work canonically.
Just make it so it's impossible for UNSC to win the space battle, their aim is just to destroy as many Covenant ships as possible/lose as little of their ships as possible within a time limit (maybe no time limit, idk), and that decides how much stuff the covies get in the ground engagement.
This was suggested in a thread AGES ago, way pregame, and is the only suggestion for space battles I've seen that I think would actually work well.
I'll also be posting this in Shadow Titan's thread.
Onto the topic being discussed, not the thread topic, shotgun whoever gets LOTS of Seraphs.
Beware the Australian Fridge
Veraam:
One with power = Corruption
Two with power = War