First, the Prime doesn't have rear automatic braking, it's just an "alert". (Other Toyotas have it and it's labelled as "Rear Cross Traffic Braking". The Prime has "Rear Cross Traffic Alert"). It's tied to the Blind Spot Monitoring System. Just go into your Settings in the MID and turn off "BSM" From the owner's manual:
Now I realized he might’ve been talking about ICS. In that case, turn ICS off in the same settings page.
Hmm, I don't know the answer to the question posted, but I would love to see the photo of a Prius Prime pulling a camper. I might have seen such photo on Gen2 and Gen3 forum, but not in here. I wonder what kind of EV range and mpg it can get???