This mod has now moved to Mod DB: http://www.moddb.com/mods/trivial-options-mods-pak (For Rebellion 1.84 or later)

I think it is probably not very widely known that there is a red skybox (or half of it; it does not have the irradiance.dds texure) in game that is not used by any stars.
Here is a mini-mod that has been sitting in my hard drive for quite a while. It works fine with v1.82.
- It makes all stars to potentially use all skyboxes (except the green one).
- Green skybox is only used by the green star. (I don't like the green skybox much).
- IIRC, I also changed the nebula assignment, such that red nebula is used by red skybox, green nebula is is by green skybox, orange nebula is used by skybox5 (the one with an orange equator), and plain nebula for the others.
Link:
http://www.mediafire.com/download/ov4317mxh5vjjm3/Skybox_all_2014-06-19.zip
Alternatively, here is a zero checksum mini-mod that merely replaces the green skybox texture with the red skybox.
http://www.mediafire.com/download/a00n40cfx88xo6w/Skybox_no_green_0cksum_2014-06-19.zip