If you haven't already found something I've been doing some research and found a couple of other options. Carjoying they make full android radios. It's like having a phone in your dash and you don't need to plug your phone in to use half the features and it's very cheap. I'm not sure of the quality though seems worth a shot. Pity pioneer doesn't do something like that.

I'm also looking at odroid you can build your own headunit, maybe a little overly complicated though.