How to work around PIE_# map names?

I’m trying to test a networked game. I’m using release 4.9 on Windows.

When I spawn two windows, client 2 builds the level name “UEDPIE_2_SetupGame” from the actual name “SetupGame.”
When client 1 comes around and tries to join, it fails loading “UEDPIE_2_SetupGame” and the session ends.

How do I work around this?

Warning TravelFailure: LoadMapFailure, Reason for Failure: 'Failed to load package '/Game/GameClasses/UEDPIE_2_SetupMenu''. Shutting down PIE.

The “how to test multiplayer” documentation and tutorial just talk about how to launch into a map with a listen server, and launch into that same map with a connecting client.
That’s great for debugging gameplay on a particular map, assuming no other setup needs to happen before that.
However, for a game that requires significant configuration before play, and that uses ServerTravel – how do I debug this with play-in-editor?
Or even if I stuff all the necessary state in GameInstance on client and server, and use OpenLevel, I’ll run into this same problem – how do I debug map loading when starting from the editor?