pick: offline - survival - map 5 "marooned"
-have the 2x missile launcher (Wallagis WarHound), the other weapon is unimportant
-get into the mech right behind you
-begin to completely level the place - you don't want anything in the way for wave 3.
-wave 1 is a bunch of ants
-wave 2 is a bunch of ants and spiders
those two waves have a total 76 ants and 26 spiders
-wave 3 has six or so bees and a ton of gunships.
if you go for bees, they take 4 RL full lock-ons or 8 rockets of the mech.
if you go for kills as well as the 10,000 gunships ach, farm this a bit, but there's a better spot in 3-3 with a theoretical endless spawn, which you actually can just rubberband with a missile launcher.
one gunship takes one missile, so try and mark two different ones per shot. gunships are also invisible on their initial descending, so wait a bit until they scoot off to the side.
depending on how you get pummeled in wave 3, you'll end up with between 130 and 160 kills. rinse, repeat. just hit Y, all your kills get saved.
one such a run-through takes about 5-7 minutes, so that's 2 waves and ~150 kills in 5 minutes or so.
if you want to survive wave 3 for whatever reason, ignore the gunships and take down the wasps first. try to make the most use of the mech and then missile them down.
always keep in mind - if you want both missiles to hit the same target, you just need to lock onto it once, not twice.
so, instead of my estimated 60 hours of online survival (based on having racked up 2500 kills in about 20 hours of survival), this took me about 6 hours, while watching evo on stream. i'm still lagging a bit behind on rounds, but this also seems the easiest and fastest way, besides letting yourself get dragged through online survival. also gives a nice boost to spider and gunship kills as well as helps with any remaining bee kills.