Doug
It sounds as if you have a shaft seal problem (engine end of shaft) not a cutlass bearing (prop end).
On rascal my 26 I had a Norris lube seal which is oil lubricated, but it ran hot, 80 degrees plus. I also got through cutlass bearings about every 2 years.
I changed the shaft seal to a RMTA seal which has a water supply from a tee fitted to the engine to exhaust feed pipe.
After some initial problems this has worked fine for 2 years.
The introduction of a water supply trough the shaft tube seems to clean the cutlass bearing as well, as this does not seem to wear anymore.
Rascal often sits in the mud on the mooring and I frequently dry out during the season, which as you say can introduce air lock to the shaft seal, I also think the muck that gets into the cutlass bearing increases wear here.
A water cooled shaft seal (with a water feed) solves the air lock and keeps the cutlass bearing clean.
I hope this helps
Philip