Check the "usual suspects" first, those for me are the oil drain tube to hose junctions, and the oil fill tube where it screws into the the case. You're right, oil can travel in surprising directions and distances. Next suggestion clean the engine well with stoddard solvent, go fly one trip around the pattern and have a look. If you can't solve it try the uv engine oil dye and a black flashlight. I've seen foot powder etc tried but it makes a bigger mess than the oil leak.
Good luck
Tim Andres