Reversing Camera cables etc " van to car " . What plug ?

I am a cretin with car thingies .

I have had a camera installed on the back of my car and a screen on my dash . This all works fine .

Now I have mounted a camera on the back of my 16' van and I am going to run the wiring down a conduit from this camera to a plug at the tow ball . The guy who did the car , will then run this camera wiring through from the back of my car to the screen with a switch to change from one camera to the other .

What sort of plug should I use to bridge the gap or does the wiring go through the big trailer plug like the other stuff ? Yes , I said I was an idiot , and no , I really don't know and I need an answer .

Thanks ,

Willie