A wired camera is easy and relatively cheap. The connection plug can be wired next to your 7 pin connector and break away cable so it is not forgotten when unhooking. That said I would not depend on any camera over a good set of mirrors.
If people are tailgating you they are at fault not you. If they are not right on your bumper you will see some portion of their vehicle or its shadow with good mirrors.
I can see any cars that are following at a safe distance behind me in the mirrors. Maybe not the whole car but I can see enough to know they are there.
I do like my camera view but it can get distracting to have a screen in the cab. I have to break myself from looking at the screen instead of my mirrors and the road ahead.