I have a corded system, similar to that one on Amazon. Got the components (much cheaper) on eBay.
I wired the truck with cable long enough to reach a camera on back of my truck camper. I also have a camera mounted on rear of travel trailer. The trailer is wired with cable long enough to reach into truck bed and plugs into same cable that is used for the TC. The monitor clips on, over my rear view mirror.
I have a third camera that I can clip onto my license plate while hitching up. I can put the hitch ball directly under the trailer coupler, first shot. Even with truck camper loaded up, I can hitch up to my utility trailer, by myself.
Most kits come with instructions to wire into reverse lighting circuit. That only gives you video, while in reverse. I made a power plug (parts at Radio Shack) to use the power outlet on the dash. This gives me video whenever ignition is on.
Going down the road, in my side mirrors, it may look like a vehicle is beside my travel trailer (especially on the passenger side), but, if I can see their headlights in the monitor, I know they are behind. I don't know why, but it seems a turn signal, only indicates the side you want to be passed on.