I don't have a picture here at work, but I did what you are talking about. I took a M105 trailer harness from the Packard connectors to the plug. All but one of the Packard connectors had already been cut off, which is why I got the harness for basically nothing.
I have the proper wire number diagrams and list, my plug in my truck is wired correctly, but just to be sure. I plugged the harness into my truck and turned on the lights. I verified that the properly numbered wire had power with a test light. I did this with all the functions needed for a civilian 7 pin plug plus my electric trailer brakes and put new numbered tags on the wires that weren't marked. Then it was just a matter of installing the 7 pin plug, zip tying the thing so it wouldn't pull apart and wrapping it up so it wouldn't short on anything.
It is really too long, but on the 715 which has the trailer plug just inboard of the left tail light. I can plug it in, wrap it around the drivers side bumperette, over the pintle hook and then around the passenger side bumperette and still have plenty left.
I can try to get pictures tonight if you want them. You are running 12V to your trailer right? Otherwise, you will need to change out your trailer bulbs.