To create something like a Death Star, with the need for totally un-distorted UVs perpindicular to the Y-axis, one would want to use a cylindrical projection method with a pair of fairly large endcaps done with planar maps. That's about the only way to do something like that without undue distortion. You'd have to map it very carefully to avoid having a seam, but other than that, it's a very practical way of doing things. Seams are much easier to avoid with mechanical objects than with organic, flowing things like planetary surface imo.

As for the rest of the issues... I have found some people online who may be able to assist our efforts and shed some light on the practical methods we would need to use to create maps without distortions at the corners (or, at the very least, less distortion). While I am not especially concerned with this issue myself, as I am not really interested in making maps of real objects in the Solar System, I would like to see if these things can be made more practical for the community, and have taken some time to try and bring this about. Please be patient while I wait for a reply to my emails on this topic.

i´ve found some new planets somewhere that are cmp-file based. I put one in a system for a test (It looked like earth) but they were invisible in the game.