5.7 crusader raw water cooled leaking water underside of starter

So, after the Chinese Fire Drill, Not an engine water leak after all, just bilge water getting into the flywheel housing??
Now where did I save that stale noodle to beat you with.

Can you enlarge the limber holes to keep the water from puddling under your engine when the bow comes up?
How about Skippy J's idea about a low water bilge pump. I have one in my ER sump.

There should be a tin cover over your lower fly wheel face. Shaped like these teeth -->. This may help reduce large amounts of water splashing on the flywheel or at least slow it down greatly. Don't seal it, you do want water to drain from it.

Do you have room for a top mounted starter? This requires a different bell housing, starter and that tin cover. You may or may not need another flywheel. New starter will be hanging high & astern from the 1;30 position behind #8 lung.
Thermo-Electron (Crusader) & Mercruiser used a lot of these keeping the starters out of the bilge.

Keep the M-Inlaw & cattle in the rear for a few minutes before starting the engine may help.
Or just grease the ship out of the starters your installing and rotate before failures..

Assuming it's in salt water, 1t would be best to remove it and have it cleaned, lubed, and protected. The probable outcome if you leave it or treat it from the outside is that bendix drive will corrode to the shaft and stop engaging to start the engine. Bendix drives can be cheap, so maybe throw a new one in. They often have a sprag-type clutch inside of them that also don't like water.

It's a new starter, read above.
The Bendix does take the blunt of abuse if water spins off the fly wheel. Sadly, if to much grease, oil or any lube makes it to the Sprage Clutch inside of the Bendix assembly, it will slip and not turn over the engine.
You have to determine where the previous issues have been and apply grease just to those points.