So, after asking a Mod, he said that it IS viable to kill enemies AFTER completing the Level, IF you can see that I still got him, which led to me trying out this new route. Could've been faster at the end and also some bits in the middle, so gonna improve this.

PS: That first bat is SOOO hard to kill like that ;( Oh, and that squeak in the beginning was me doing noises out of frustration xD