A while back there was mention of the build settings getting multiple targets in the editor.
It’s doe not even seem to be on the roadmap.
Will cardboard and oculus become native and combinable?
Different market places and free vs pro builds still not a simple solution…
Is ‘Advanced Builder’ the only option?
Or are there some tricks we can already use?
I should really look into the command line tools, but will that even help?
One neat trick is to use editor scripts in scenes and flag the object with EditorOnly 
It would allow us to inject stuff into a scene, just as it is being built (using things like PostProcessBuild and PostProcessScene).