So one problem we run up against is that the player is already started (and in most cases is talking to the serial port as it wasn't started with -s-)
So, for GPS type apps this won't do.

Surely the Kernel controls all low-level I/O and can intercept calls to files on the hard disk at any point in time. It could, for example, say "every time someone tries to execute empeg/player, add the -s- parameter".