AutoMate is not going to work. Here is a fragment from a Google Groups discussion :
...............................................................
Well, the app tries to simulate the behaviour of Android Auto and it does it in a nice and good way (as much as it can). Like you said telephony will not work because it is not installed on the phone and head unit will not be able to dial out directly, you can try to use TabletTalk to dial out, but if you do then on incoming calls it will display a floating widget over any app, which I find very disturbing when using navigation, so I have given up on that.
The full discussion is available
here.