The boat is only ever on its trailer for the winter, and this winter it won't be stored on its trailer unfortunately. I agree that running it on a hose and measuring water output on each side - not just guessing but actually measuring - is an exercise worth doing, although probably in the spring at this point.
The RWP housing runs extremely close to the temp of the lake, I've checked it with my IR thermometer. And when I winterize it, I sort of do the "bucket test" when I suck up antifreeze... but there again I should *measure* the time it takes, which I never have.
Thanks again for the thoughts and ideas. I think I just need to be a little more methodical about this, rather than assuming something is OK because it "kinda seems normal."
The good news is, I had a whole season without a single hiccup with the boat, over 60 hours and the only "issue" I had was re-packing the stuffing box (which was by choice). Oh and the Keel Guard is delaminating, not from the boat, but from itself. That I can live with, if it's my only problem this season.