Take your best ranged weapon (rocket launcher over missile launcher) and best automatic MG. Try and take out as many from as far away as possible and mop up with that auto when they get in range. Keep an eye on the radar and try putting a wall behind you as you whittle the packs down. It's rough going, but can be done.
The missile launchers on here are total garbage. I never liked using rockets because everything swarms in and jumps in front of you when you trying to shoot the next group coming. I miss those auto locking missiles from EDF IA that did 0 splash damage even when you shot stuff point blank. I almost always run AF100+Lysander Z. I've tried the shotguns/flamethrowers for missions like 52, but the shotty takes forever to reload. You can't even move to walk over health packs or see where they are half the time.
I think I had around 25k armor by the time I was able to finish this same mission on 2017 (I think it was like #46 or 47). I guess I'll farm more. I skipped this one and kept failing 74(?) too for some reason. I'm surprised I was able to survive 79. I was really laughing on that mission you have to shoot the bee hive (69?). I died, but the hive was already dead so it kept falling and said "mission clear" while I was dead on the ground. lmao
Finally. 25k armor on Ranger and like 2800 on Air Raider split screen myself. Put ZEX guns in 2 slots of Air Raider, AF100 + ...MF rocket on Ranger. I used one set of ZEX guns right from the start and laid out the other set for the 2nd group coming behind me. Ended up with enough health packs lying around to clean it up with the rockets and AF100. I just did 85 with Ranger + Wing Diver. I still have 81,82,84 and I'll have Ranger complete on Inferno.