CCC-Max

Hi everyone, new member here. I just purchased the C-Max Energi and I need clarification regarding the brake lights. I noticed many folks are adding on light kits to the C-Max for when they are being towed by an RV. My question is: 1. If I have a dedicated 12v line from the RV to C-Max battery AND 2. I have a dedicated 12v from C-max battery to the supplemental braking system (i.e. like a BrakeBuddy) THEN can I just use the regular lights that come with the car and not install more light bulbs into the tail light fixtures? I'm "assuming" that when the RV sends a braking signal to the supplemental braking system, the brake pedal is depressed and then the normal brake lights should come on. Please let me know if I'm missing something in my logic and that might explain why others are adding light kits.