I have an idea instead. Let's take this the opposite direction. Instead of placing the onus on the players to get consent from each individual player, let's just put a trigger warning directly on the website:
"If you are disturbed by adult themes like murder, torture, sex, betrayal, theft, animal cruelty, slavery, or virtually any other horrible thing you can imagine that might happen in an RPI game where no consent is required to kill you, this probably isn't the game for you. If that's the case, thanks for stopping by. If not, welcome to Armageddon!"