I have put no specific investment into the toons/ships required for that mission. so you may want to rethink what you think are the requirements.
boba and Cad g12
vader/TFP/KRU and Hux were all g12 when i started beating it, now they are various R levels for GLK, Vader is R3
I only just unlocked the 5th star so I didn't use Kylos shuttle, and i still dont really use it but its in the reinforcements.
the mission is more about kill order than anything else.
each time the event comes around you can repeat the final tier to earn shards, its farming like a node, but at a different pace.