Impossible to overtighten the
oil pan. It has plastic bushings around each bolt and there are "spanner' flanges. The
oil pan set up is a work of art on your engine. I doubt it is the
oil pan.
It is very possible it was the back of your manifold, nobody realizes yoiu must retorque the manifold bolts through 8-10 heat cycles before they stay tight. I am not saying that is right but that is the way it is.
Once oil drips it takes forever for it to stop even after the leak is repaired since all the oil on the porous block eventually drains down over weeks.
I would focus on the plastic oil line. its a finicky push pull connection. i would tell you how it works but i am afraid you would misunderstand and then the line would blow off as you are driving down the road. My guess it the oil line or intake manifold OR you valve cover gaskets. Did you torque you valve covers they like to leak out and drip down the back. if it is the rear main seal, live with it, its not worth getting into!!!