How about this as an idea:
Under normal conditions, saving the service does just that. Saves just the service order.
On the file menu, there could be a "Pack Service for transport" this could create the service file as it currently does, or save the service, creating a "service_files" folder with all songs, images, videos in etc. (much like saving a web page used to)
Either way, maybe a progress bar could be implemented, a bit like when the image thumbnails are being produced.
Phill