Ziz said:
The only time trailers have music from elsewhere in them is the early ones before the film has a proper score to pull music from. The music is as much a part of SW as any other element. It wouldn't feel right to change it.

Your first statement is simply not true. Countless final trailers feature music from different sources and not the movie directly. There are even composers/companies out there who create scores just for trailers (ParodiFair, for example, though I'm unsure if they're still in the business). The music of Star Wars is epic and is instantly recognizable as Star Wars in any context. It just isn't an absolute necessity in EVERY modern Star Wars trailer. Look at the trailers made for the defunct Star Wars: Reborn trilogy. Not Star Wars, but very effective.

I'm thinking more along the lines of some obscure instrumental metal tracks, not a piece taken from another movie's score. Hell, even a track culled from classical music would be nice. Just not something easily recognizable, or beaten to death ("Carmina Burana" anyone? - I could live a long, healthy life without hearing that in a trailer ever again.) Most of the epic Star Wars cues have already been use ad nauseam in the trailers already out there.

Obscurity is the key. You cannot plunk down a Star Trek track or any other instantly recognizable track in the background of a Star Wars trailer. That wouldn't sound right. Something less known is needed to make the whole two minutes gel.

Ah, the hell with it. I need to learn some video editing and I could show you what I mean. Now to learn how to edit, that's the real trick, isn't it? :)