Credit for the video goes to McWilly
This trophy can be fairly frustrating, mostly due to the fact that you can't restart from the previous checkpoint, meaning you have to play through the beginning section where you attack the boats every single time. To minimize your frustration, make sure you have your sensitivity turned to low (pause, go to options, sensitivity). Another extremely helpful thing you can do is turn off controller vibration (hold PS button, controller settings, toggle vibration). Lastly, watch this video as you go through, pausing the game and watching the upcoming segment so you have an idea of where the planes come from. This was EXTREMELY helpful for me. My first tries before doing these things got me about 30 kills each time, the first time I did all this I had 45 kills before the final section (on the front gun) and ended with 67 total.
NOTES: When you shoot a Zero and it begins to smoke, it counts as a kill. Listen to your crew mates, they'll occasionally call out where planes are coming from (it may help to turn on subtitles)