, I was in the same boat as you. My Jeep was NOT prewired.
I opted to go with the OEM hitch because to me, once it's installed, it looks a ton cleaner than any other options. Yes, the lower bumper must be cut to use the OEM hitch. We ran the new harness from the TIPM (engine bay) to the connector which is installed adjacent to the hitch. Per Mopar instructions, the light blue wire for brake control was to be secured behind the glove box...which obviously we took a different route for install.
For the brake controller, Jeep offers a brake controller integration harness that saves a lil bit of wire splicing and definately makes the install go quite smooth with minimal knuckle skin sacrifice.
With the OEM harness and as other have stated, this MUST BE ACTIVATED VIA STARSCAN. In the end, it would have costed ~300ish parts/labor as other have mentioned, but I had this included in the purchase of the new ride.