Why not submit the planets to the
image mod instead? There is already something called a planet pack.
Also, the system images might be better off having different names (adding a short prefix as in "pre_nebulae2" is handy) so that they do not conflict with other mods. A simple data mod can be provided to use them instead of stock images.
It is a good idea to remove thubs.db from archives. It si a useless file to the rest of us' and is making your planet pack at least half a meg larger than it needs to be.