The tenders are not all identical, but the concept is the same. Yes the truck had to be removed to get to the claw and pull the harness out for the electro coupler. I then used some black RTV to seal up the hole where the roller pick up wires come up through the frame. Maybe you could just cut everything off from the bottom, but that's not how I do things. I like neat and tidy, like it came from the factory that way 
Here's the Legacy AC12:
This is actually much easier than a diesel conversion because there are no steps to build a spacer around.
That's a 740 coupler with the draft gear ground down for clearance as I show in one of the Kadee Coupler videos I've done. The coupler only screws to the pad, and then the outer holes on the pad mount the pad to the tender. That keeps the mounting screw far enough back to go into the frame of the tender and not through the step on the back.
