The almanac has already been made. I extracted 3 pages and added them to my F1 help file from:
http://www.subsim.com/radioroom/showthread.php?t=138585 - the Combat Information Center mod and I find it very useful. The full moon and new moon phases, moonrise moonset times seem to be pretty close as well as sunrise sunset times but I don't want to get jumped on for saying that. They are close enough for me considering this is a game.
This same information is available from NASA and maybe it is in other mods.
You sound very ambitious if you really want to fix the SH4 sky for navigation - if it is even possible(??). Good luck if you do!
Happy Hunting!
Art