All 6 acorn nuts had oil on them, meaning oil was leakin from around the studs. I was going to drain the oil and reinstall new gaskets, but there is no leaking around the edges of the sump.
So I decided to take off each acorn nut and copper washer 1 at a time, clean them, add RTV to the base of the studs, and reinstall the copper washers and acorn nuts (photo 1). We'll see how it holds up.
At my DAR's suggestion, I also installed an aluminum screen material over the cabin heat air intake, to keep out critters (photo 2).