Not sure if you HAVE to have the connections installed in the passenger kick-panel to get the rear connectors hot... But, you get those passenger kick-panel connectors INCLUDED with the $55 harness.
So, just install them, it's like 5 more minutes. The instructions are a little ambiguous though, don't skip over anything.
The hardest part of the whole project is determining how to mount the 7 pin plug to the hitch. If you have a factory hitch, it's no big deal as there's a bracket pre-welded. A non-factory hitch has no bracket, so I had to fab my own.
Good luck.