PS: Obviously I have setup a mod folder, have a PlanetDefs file (append style) and StarsystemDefs file (Non-Append style, as append style doesn't work for this file both pre and post Crusade).
I also tried just taking the Sol system entry in StarsystemDefs, copying it, changing its internal name/display name, and just having it sit right above the Sol System entry. Again, custom home system appears and is selectable and upon launch of a game, you crash.