Unfortunately, that was my main idea 
My other two, less exciting ones, are
- I assume you have the level you want to run in
- You can also make a new empty project ( start the engine from the Launcher, new blank project ), and migrate only the map you want to it, and package from there.
If the map you don’t want gets migrated in (2), then that’s more info. If not, I think it should work… 