Question:

[RidgeRunner]

Popcorn... Must remember the popcorn...
My flats boat with the jack plate all the way up puts the cav plate (anti-vent plate) nearly even with the surface of the water. At idle I do think there might be a problem with prime on a centrifugal pump.
Not that it matters much, they make positive displacement pumps with harder vanes than the rubber impeller we see in the modern outboard. Jabsco makes a hard vane puppy pump that I like for fuel transfers. Debris MIGHT be the only spoiler and I know it will move a lot more debris than you would ever want in the water jackets of your outboard.
I am not arguing, The question has no correct or incorrect answer!