I have my Empeg trunk mounted in one car with an infra-red radio repeater allowing me to point the remote at the dashboard to control the unit in the trunk. I have pin numbers assigned to every playlist so that I can choose them without needing to see the screen. This works nicely.
I'm about to have the 2nd cradle fitted in the glovebox but won't bother with a repeater this time as it's very rare for me to do anything with the Empeg other than use it as a very large CD changer and on the very rare occasion that I want to use the pin numbers to choose another playlist I can reach over and open the glovebox and point the remote in there.
In both cases my Empeg feeds the line in channel on an existing headunit so I don't need to fiddle with the Empeg volume, radio, etc..
Both installations by Dominic at Cambridge Car Audio, who I strongly recommend.
Cheers,
Mark.