I like figuring stuff like that out too. In "Ships of the Starfleet" some ships got rid of the big clumsy deflector dishes and had slim rectangular deflector emitters at the leading edge of the saucer, like you suggested, called "WADE defelctor units". I think they must work better when the emitters are outside of the hull, I imagine because a starship's hull, unlike the nose of a jet aircraft, would be shielded and reinforced to keep OUT radiation as much as possible. The reason the radar dish is inside a nosecone on a jet plane I might add is because you need a pointy aerodynamic leading edge to pierce the wind resistance, whereas it would probably be better for the radar to be uncovered, like on an awacs plane or an aegis ship. That said, it's probably better for defelctors to be outside the ship as well, because they not only emit gravitons and EM but can be configured to emit all sorts of interesting things, as we've seen, which a hull might interfere with.