That doesn't work very well in the game, because the gunners fire in salvos and will often pause for some time and then start again, that's what makes identifying dead gunners so difficult.

hitbox for gunners is pretty small, iirc from using arcade=1. as in rifle calibre bullets have to hit their heads. fragments from explosive shells can kill them as well.

there was/is a quirk with the ju88 for example, where getting a rear gunner kill also takes out the pilot.

ju87 and bf110 gunners appear to have a secondary role of armour for the pilot, they die that often.

and the canny human gunner will hold fire, so you slip closer for the killshot thihnking you're in the clear, then *slap* headshot.

I still think I can make out dead gunners with greater reliability and from further out then someone looking for dead bodies through a small piece of glass.

Perhaps with a well-protected gunner station like the tail guns of a B-17 or B-25, but a dead crewman in a "greenhouse" gun station like the tail gunner of a G4M or nose gunner of the He-111 should be more obvious. Even then, the LoD structure of the game makes it impossible to pick out dead crew until you're within realistic ranges.