The other alternative that I was considering was a trunk mounted unit with an RF remote up front. Secretaudio SST. They seem to be in the $275-400 range. I picked up a $60 Pioneer unit on sale that will be good enough for now. It should be going into the glove box today or tomorrow.

I ended up deleting the little storage shelf in my design...there just isn't room for it between the glovebox door and the heater box the way I had it in my mind. So I'll keep the reg and insurance card someplace else.

Later I can easily switch to that SST system if I really want that glovebox space back.