Don’t call him out or anything like that. You and your friend should make sure there is no interaction that is traceable. Masks, long pants, long sleeves, are a must. Park far away and have a change of clothes. Hit and run style. Watch him for awhile and get some form of information (when and where will he be, who is he with). Run up ( no cameras no witnesses) smash him up. Maybe take a wallet(throw it away when you leave DO NOT USE IT) run back to your vehicle. Change clothes (maybe hide or burn depending on the beating) never tell anyone afterwards and certainly don’t mention the rape during the assault. Also don’t speak during the beating unless the emergency. But also this is illegal and you shouldn’t do this but sounds like you’re going to anyways so be safe but also you could just run a “public awareness campaign” beating heal but that shit will stick and it’s legal.