Mine is a DDPAI mini, very similar to the one recommended. Small and discreet, just what you want. With a WiFi connection to your phone you can watch and download all the footage without needing a screen on the camera.
At the time it was on offer for £49
I would recommend routing the cable down the drivers side ‘A’ pillar rather than the passenger side. There are no cables on the drivers side. I had an issue on my first ND using the passenger side and trying to fit in more cables which distorted (ever so slightly) how the ‘A’ pillar cover connected back into the head lining cover. (Albeit I was installing welcome lighting cables at the same time).
On my new MX5 all cables run down the drivers side.
I wrote a post about that install here:
Granted it was a bit of a faff getting the cable back across to the passenger side to connect to the accessory socket.