Is there a way to set a dropdown by it's external id?

Not as a parameter with the setValue call; you would need to make your reference externalid to internalid object/list and get the value to set from that.

Yeah, so basically create a search and look it up by external id. man, was hoping there was a way

It would be really nice if External ID behaved that way, but sadly no

Agreed. Thanks you guys!