I decided this was likely an engine-out fix, and since I already had to redo a fair bit of wiring, and there's plenty of snow on the ground, there was no time like the present. With the rear cover off, I began inspecting the the seals and holes to try and figure out where the oil was coming from.
To my astonishment, there was actually an open hole below the pump cover. After visiting the CX500 forum, I discovered this is the weep hole, and it is designed to release pressure if one of the pumps fails so coolant doesn't flood areas it's not intended to. Tracing this passage back to it's origins, I found the source of my leak to be a blown out oil seal, as pictured below.
What was more concerning during this repair, was the small pile of mystery parts in the bottom of the bikes rear compartment. Amongst the oil that didn't drain, was a small pile of metallic engine jetsam. One, a long tightly wound spring, reminded me of the spring occasionally on a mountain bike fork seal, that has a purpose but is not wholly necessary.
The other parts, appeared to be more substantial and had me quite concerned.
