I decided I didn't really enjoy the tablet install, so this will now be the 3rd revision of the MX-5's audio setup.
Goal was to create an even simpler interior, might even delete the AFR gauge, by relocating the head unit into the boot/trunk. I still wanted to retain full audio controls as well as Bluetooth and USB connectivity. My old audio setup worked well but the sound wasn't the greatest, probably from the lack of pre-amp/equiliser control.
Although I planned to mount the head unit in the boot, I still wanted full control of the unit, this was achieved using an IR repeater. Normally used in home theatre setups. Simply have the repeater eye in the cabin, and the repeater transmitter in the boot with the head unit.
First thing was to make up an extension harness that goes from behind the tombstone and into the boot. I used roughly 5 meters worth, and I went with something more flexible, conductor is 38/0.15 strands. And I've just terminated the ends with connectors.
Pictured below is the IR receiver unit, I've mounted this just above the rear view mirror. The harness was plugged up, and you can also see the little USB power adapter that's powering the IR Repeater.
This is where the head unit will be mounted in the boot. I've made a cardboard template for that little spot and will make it out of marine plywood and covered in automotive carpeting. You can also see the IR transmitter double sided tape right in front of the head unit's IR receiver, and the right angle USB extension cable.
The completed setup, showing how much simpler it is now. The other end of the USB extension sits in between the driver and passenger seat, and the remote control has some double sided velcro to keep it easily accessible.