Certainly looks like a lot of crud under the skid plate. It can hold a lot of oil. What I would do is buy a couple cans of brake cleaner and clean it up real well. Then see if it leaks. If you had a leaking oil plug or oil from the rear main leaked down inbetween the skid plate and there is dirt packed in there it can hold quite a bit of oil and weep it out over time. If so you have 3 options.
Take it off and bring it to me and I can fix the leak. Find a used pan. Or buy a new one.
I can brase the spot welds so they won't leak.
Rear main looks to be leaking but without taking that little cover off and looking up there you will never know. There are other places oil can be leaking out of besides the rear main, Cam plug, Oil pan etc....