Flying Unit/Strider Pathing Question

[Cozy]

I have all non-traversable areas of a map cut off by npcclip brushes. Is there a way to make these sections so that flying units, striders etc. can move through them while still ensuring that normal units don't fall off/run out of their playable area?

EDIT: It works if I make the npcclip brushes shorter, but then I'm afraid that the vortigaunt can send units flying out of bounds.