Originally Posted by dan-fox
Since it's a "van" is there any chance that you could get a pre-wired plug-compatible harness from e-trailer.com or similar? I've had good luck going that way with passenger vehicles.
I would be surprised if this is a viable option, as most body manufacturers supply their own lighting wiring.
What I've done is to simply run wires from the lights in question down to the trailer plug - which should be fine if your trailer doesn't have a ton of lights and won't draw much current.
Should you have a trailer with a lot of running lights, you might consider running a thick wire from the battery and using a relay to switch it on/off (I may do this eventually if I anticipate heavy electrical loads.)