Yes, engaging reverse activates the front sensors.
But so does pressing the "P" button on the centre console, it toggles the front sensors on and off, that's what it's for.

 

I wonder if I could just buy a front camera and a Fakra-RCA cable and splice a camera into where the OEM reverse camera one goes (i.e. the purple post next to the M.O.S.T optical connector) and trigger it with the P circuit switch + a toggle switch? i.e save on the $550 CAM unit.

So OEM one works with no changes and front comes on when P is pressed and toggle switch pressed. Assuming the head unit over-rides the screen image when a signal is detected on the camera input.

Ebay sell a Fakra-RCA splitter cable to make it plug and play.

http://www.ebay.com/itm/RCA-female-J....c100005.m1851

What do you guys think?

 

Sadly there is no P circuit switch - the entire button panel is self contained and generates control messages sent over the vehicle's MS CAN network.

There is no automatic override to change the video signal, you need to run the correct app on the touch screen OS which is only activated when:
1) the vehicle is put in reverse, and/or
2) the P button is pressed and then the Camera soft button is pressed.
The app is loaded based on certain control messages being received over the MS CAN network so it cannot be triggered with a hard wired solution.

I forget which sex is which on the downstream connector (C32S/T), but yes you can easily feed your own video signal in at that point. That is easier than directly behind the touch screen as you can route your new cable to the void between the seats which is a handy place to put any extra modules, etc. FAKRA Z keying (turquoise) will fit all other FAKRA keys. I also forget which video format is required as it was some time ago when I worked with mine. You need to be careful with the voltage used though, it is probably using 5V.

If you fit the OEM roof switch (£50) plus a suitable wide angle camera (£100 for a good one, cheaper will work but might not be a good resolution) and an automotive rated* latching relay (£10) you can do it for much less than the nav-tv module. Their module sits on the MS CAN network and reads/sends the control messages to function - with the OEM camera (or by enabling it via the CCF) you don't need that level of functionality just to get a camera image working.

* Should be rated for -10C to around 80C

(It is worth noting that I have only worked with the pre-2016 cars using the IAM-based infotainment systems. Those using the media gateway (newer Ethernet infotainment) may not function in the same way.)

 

This is the camera I was thinking of getting which is composite output and I assume this runs on 12V. The roof switch is part number T2R1879.

https://navtv.com/products/NTV-KIT38...a-5-front.html

The 2016 have the 770W meridian system. But I cant find what the video input is from the OEM reverse camera to head unit i.e is it composite or a higher level? i.e will the above camera work or do I need something that is compatible with the OEM camera. Guess I should try and find what output the OEM reverse camera (part number T2R14120) is.

I assume I would power the camera via a replay connected to the Green/White wire in junction box, brown connector that triggers on Revers selected or P pressed. Then the roof switch would splice into the Fakra-RCA splitter to switch the signal between reverse/forward camera.

From the NET-TV manual.
For 2016 vehicles, reverse does not switch with CAN data. Wire a 12v SPDT relay (not included) like this:
a. OEM reverse signal (+) to terminal 85: (Green/White wire in junction box, brown connector, see image at right)

Note Im not an expert in video signals!!