I just finished this project earlier today, some input would be great if you want to test it out here is how:
Download Link here: https://www.dropbox.com/s/1z59qro5y1wjjci/NuclearMissileMod.zip?dl=0
Install mod by extracting the zip file to your .../Cosmoteer/Mods/ directory, in that folder should now be a folder called "NuclearMissleMod" If that is there than proceed to step 2
Launch game, and start a new game/load an old save. *I would advise backing up save files before installing any mods.
It works just like regular missile systems, but you need to use all of the nuclear parts, which are about 2x more powerful but around 2-3 times more expensive.
Hope you enjoy! Let me know if anyone wants anything specific when it comes to modmaking. I have quite enjoyed how simple (ish) it is to make mods for Cosmoteer.