i know that is not every time the best way to put to much reality in a game, particularly because Freespace is fiction.
but i think only a point starfield and some nebular are not enaugh.
i think we there a little bit more diversity, too.
Merphack there is no real problem trying to extend FS universe for personal use (mods, campaings), though, yes I am careful as you when talking about FS Retail campaing, remember that fiction doesn't is always an attemp to modify or harm reality, but sometimes just extend it, it has already happen that fiction has become reality in many cases.
I bet that warning was originally to prevent the original FS from being too modified, and mainly to stop requests...
Anyways, if you want to make something real you can check here, this is regarding more Nebulas, (I am not too sure but I think the starfield is done quite complex in Celestia, that means drawn point by point with an X,Y,Z location, intensity and some other artifacts)
ExtraSolar Nebulaes: Messier Nebulae:
http://www.celestiamotherlode.net/catalog/messiernebulae.phpExtraSolar Nebulaes: non-Messier Nebulae:
http://www.celestiamotherlode.net/catalog/nonmessiernebulae.phpExtraSolar stars (but there maybe something to complement an Starfield)
http://www.celestiamotherlode.net/catalog/extrasolar_stars.phpGalaxies:
http://www.celestiamotherlode.net/catalog/galaxies.phpOr you may want to check the Homepage of Celestia Motherlode (but there is nothing more there related to Starfield), they do an excellent job in the rendering of the overall know universe :
http://www.celestiamotherlode.net/----------------------------------------------------------------
There is a lot of media to start with here, All of this media (Nebulas/etc.) just need some format conversion in order to be used in the SCP, sometimes you'll see they are using DDS format, anyways without some "average" knowledge about the media you download you won't be able to really define what you're supposed to represent...(some files contains Readme files with accurate data, so you can get an idea on where in the universe the nebula or other media is or should be located).