I have a wireless. I cut & spliced the camera & power cables & moved the transmitter closer to the monitor. Perfect reception now.
As mentioned above: There are transmitters and receivers you can use
Amazon page of transmitters and receivers that you put close to each other on either side of the hitch and wire the rest of the connection.
I used a telephone jack connector and had it attached to the 7 way plug, so that every time I plugged in the 7 way I also plugged in the phone jack for the camera to monitor wire.
One trick I had to use was I put the monitor (13 in TV) in my back window and used the rear view mirror to see the monitor. That removed the reverse view I was getting from my camera, since my camera was not bu.