Porsche911GTS'16

As some may recall from my prior posts, I am on a quest to swap out my 991.1 C2 GTS rear center grill for a center tail light (a la the GTS 4). My dealership service department claims that it is not possible. I would like to inquire with a reputable body shop/mechanic to see if they think it is a possible modification. The Porsche service department claims that there is not an attachment on the C2 wiring harness for the light bar and that the car's entire wiring harness would have to be changed to a C4 harness in order to make the modification. I find this hard to believe, particularly in light of the fact that another Rennlist member did this exact modification (I messaged him to get more information but I never heard back). The search continues... Thanks for your input!