Just a thought:
Few years back, on our 60 HP 4-stroke Merc, we noticed fuel/oil coming out from the area you describe and show. It was really bad.
First noticed it the beginning of the season when in the water. You know, that glassy surface oil on the water. Then noted the fuel/oil coming down the sides. Pulled the engine cover and looked at the top of the all around-lip just below the oil filter, plugs etc. There in the bottom was a literal pool of oil/fuel floating there. Used a good roll of towels to soak up the mess. Cause was in Winterization process, oil, filter, plugs, fogging, the untrained kid (at the storage building) doing the (work) spilled from the filter etc and left it all there without cleaning it up. Yes, it scared the he-- out of us when we saw it.
Anyway, since then we only have qualified Marine Dealers do the work on our boats. No more an issue.