Well, I'm a bit embarrassed that I can't tell you. Why?
Because I have had the same (or at least it seems to be the same) leak on my 2001 for a few years now. Except I don't have it dropping onto the exhaust - I'm having a bit of a hard time visualizing that (based only upon what I know with my leak).
What I can tell you is that - if it is the same as my situation - it is not from the front seal or the cam seals. It is not from the oil pressure sensor. It might be either from a porous flaw or from a gasket for the oil pump (or something else there).
I am generally meticulous about my cars, but my 2001 has had such major tranny problems that I have come to a place where I ignore the small stuff.
And for me my leak is just a bit of a mess on the oil pan, with a drop that accumulates and then might come off of the oil drain plug while parked. (But it is pretty messy down there when you lift the car and have a look.)
In days gone by I would be "all over it". Now my attitude is that it has been that way for quite awhile, and I simply check the oil level in between oil changes.
I know this post is not helpful in resolving your problem, but just wanted to indicate that perhaps this is not atypical. If I can get myself to believe in the van again, then maybe I will explore further.
I would very much appreciate it if you post whatever you find out.
Best of luck.