Ability to use %outname% within --outer_wrapper

I'm interested in defining source maps via the command line at the same time I compile my files, using the argument " --create_source_map %%outname%%.map". Meanwhile, I'd like to automatically append the sourceMappingURL in the same command. However, after a cursory walk through AbstractCommandLineRunner.java, it doesn't look like the %outname% marker is available within --outer_wrapper.

Essentially, what I'd like to be able to do (and don't think I can) is this:
" --outer_wrapper='%%output%%//# sourceMappingURL=%%outname%%.map'"