Might be a silly suggestion, but...

For those occasions where you need some noise in the car, but then have
to park it somewhere "dodgy", and it's not feasible to pull out and carry
the empeg.

How about a really cheap FM radio that plugs straight into the empeg's
slide bay in the dash? Nothing fancy, just something (almost) disposable
in case of theft. Hell, you could even make it look like the real thing,
so that thieves don't even know whether they're going to get something
worthwhile when they see what looks like an empeg equipped car.

If nothing else, it could be useful in two car (one empeg) households,
so that the loser in the fight for the empeg gets at least something
to listen to!

Jim.