Filter covers..
"...build it into the case...cover it with a blank gasketed cover then even if the filter bowl separates for any reason the oil is trapped "inside" the Gear Box."
You still have a cover and a gasket with attaching hardware to hold the cover on, that mechanics need to remove and install during inspections.
Mounting the filter in the external system would address these human factors.
Have you ever seen a gasket blow out on a Huey transmission internal oil filter? All the oil goes away....