well, if they get too much flack for using TWOK music they could use the Krull Soundtrack- Horner stole from himself and when did Krull.
Or, they could go for an off-the-wall approach and use non-Trek scores. Jerry Goldsmith's score for The Wind and the Lion has some wonderful themes that could lend themselves fairly well to a science fiction setting. It doesn't hurt that Goldsmith reused portions of the score for the Klingon theme in TMP, and in some spots in TFF.