Thanks you very much!
There was and I think it was based on Joraks ideas. But again, it's not feasible with texture animation. One could probably have a system where there are four or so times of day and then for certain quests or after a certain time and when you change module, the next skybox would be used. But a seamless day night cycle is just not possible.
The compressed 2k tgas in my first skybox mod were between 10 and 15 MB per texture and I think that won't change much. I don't know how much I can lower the filesize by using tpc but not too much I would assume. And going from there, an animated skybox with let's say 16 frames would already be at 160MB per texture or 500MB for one skybox. And 16 frames isn't even close to being enough for a proper sky animation.