Rear main oil leak when parked on a steep hill.

More likely the rear rubber piece on your oil pan, if it's dripping that much to leave a trail. Could be rear main, but that rubber strip getting wadded up is more common. I made the mistake of using RTV on it before the last time. I thought it was my rear main, too, until I tilted the engine pulling it, and a steady stream ran out. Your bell housing was holding the oil on the hill, then running out on level ground. It stopped because the oil level got below the pan lip.