You might also pull the flywheel cover and fire up the engine. Then have a look about the area in question looking for where the oil may be gushing out. It is even possible that could be the pan gasket where the 2 pan bolts screw into the rear main retainer. Almost impossible to differentiate with flywheel cover in place.

As mentioned earlier, be very careful in ruling out valve cover gasket at rear of engine. They can fool you.

Given all that, I too once had a rather catastrophic rear main leak oil up the entire rear bumper of my car. Made a nice mess baked onto the ceramic coating on my TTI headers. Took as long to clean them as to replace the seal.