I installed a Garmin backup camera inside the rear window using some parts from my action cameras and have had success with it. The camera is plugged into a 12v
tv plug and will broadcast about 200 feet. The transmitter lays on the bed. The camera is wide angle. This is good for backing up and not so for driving. The best thing is the camera links to my Garmin GPS which is already on the dash. The one time we had problems was caused by not removing the reflectix insulation from the front window.
Next I want to try to attach an old Android phone to the rear window and link it to my newer cell phone using my truck's wifi. There are apps for home security to try. Now if I could just remember my truck's user id, password, pin, etc....