Here's what I would try.. install oem sat radio, u have the nav, put the ipod on a perminent tape modulator (lead the wire back into the head unit), and the video input you can still do.

I'm not sure about XM, but Sirius does i88 traffic every 4 minutes, and if that is not fast enough you can rig your cell phone to pick it up.

Anyway to try one out, either start calling custom installers around the area or keep asking people in the midwest forum to see if anyone has it installed you could visit.

 

1) I have the OEM sat, 2) I have no tape (2005). Hence my dillema.