For one, what tells you the first 8 camera all connect directly to the PX-2 unit? And do they produce the same video image that the rear camera does? What tells you that? Where are each or any of those first 8 images displayed.
Next, do you have a method to splice the completely separate cable from the front cam into the RVcam signal. And some kind of software hack?
I don't see it. I don't see what you are trying to accomplish with all this splcing and hacking. What is it?
The point is to switch the camera view on the CID to either be a camera placed in the front of the vehicle or for some people a camera placed on the back of a trailer. You can see an example of what had been created here: Front/Rear Camera Touchscreen Switch Kit, Camera and Cables - SOLD