Just in case anyone's vaguely interested, I just fitted a rear view camera to my Oxygen MTB, which I find very useful, as you can keep a watchful eye on what's happening behind without doing a meerkat impression every few seconds.
The (wireless) camera came from AliExpress, cost about $26, and can be ordered to either work with a 12v or a 5v USB supply. I opted for the USB version, as there's a USB socket on the battery. Once it's powered up, you select the WiFi (transmitted by the camera) now visible on your phone, and open an app on your phone which displays the image, which can also be reversed, ie to a mirror image.
I mounted mine on the end of my rear rack, and rather than feed the wire up to the front of the bike, I shortened it, and connected it to a small power pack (might need to waterproof it though) The camera doesn't seem to use a lot of power either. Pic of camera and screenshot of image attached (taken in a very full garage!)
The (wireless) camera came from AliExpress, cost about $26, and can be ordered to either work with a 12v or a 5v USB supply. I opted for the USB version, as there's a USB socket on the battery. Once it's powered up, you select the WiFi (transmitted by the camera) now visible on your phone, and open an app on your phone which displays the image, which can also be reversed, ie to a mirror image.
I mounted mine on the end of my rear rack, and rather than feed the wire up to the front of the bike, I shortened it, and connected it to a small power pack (might need to waterproof it though) The camera doesn't seem to use a lot of power either. Pic of camera and screenshot of image attached (taken in a very full garage!)