Sorry to revive an old thread but you have already done exactly what i want to do with your GPS. I was actually planning on tapping into my existing cig lighter in the console and then routing it to the left of my steering wheel but after reading your thread i guess that sounds pretty stupid. I haven't even opened my fuse door yet, but i was wondering what you used for a ground. It might be obvious once get in there, but like you, i want to plan everything before i get started.
Any help is greatly appreciated.