The view through the rear-view mirror became quite obstructed with all my construction, and when driving with luggage, it will be even worse. So I decided to put a rear-view camera in. The camera already crates a reversed image, like a mirror. This image is then shown on a small monitor above the real rear-view mirror.
I did not want to drill any more holes into the vehicle, so I decided to mount the camera inside of the vehicle. One disadvantage is that it has to look through the tinted rear window, which means that the image is darker, and at night it is basically not usable, except when other cars are there with their headlights. But this is ok - the real mirror is also not better.