Hi;
Interesting theory about the alternative "underslung" tail nav light, but I think it would not be practical to locate the nav light UNDER the rudder. Also, as I look at the photos shown (and also scanning what I have) I note that the "opening" does not appear to be consistent, and has a rather "jagged" appearance.
May I suggest an alternative explanation? Overzealous pilots.
What I have noted in looking at these pictures, and many others, is that the shape of the bottom of the rudder in some aircraft is nicely rounded, while on others it is very flat. My hobby is "building" virtual aircraft for a flight sim, which tends to make one very aware of movement and function. For instance, note the Flettner tab on the rudder which virtually all 262s had (though it is rarely noted.)
I also include this screenshot:
Though I know it is a model (nobody would let me rotate a real 262 on its tail to illustrate my point, hence this shot) it illustrates clearly that when the 262 over-rotated, the first area of contact with the ground was the rudder. I would submit that the big problem with the early tail light arrangement was that the plexi "globe" was shattered too often by pilots over-rotating, either on take-off or landing, and could explain why the nav light was relocated. I also submit that while metal may dent, the wooden rudders would be more prone to shattering, hence the rather jagged nature of the bottom of the wooden rudders illustrated.
Certainly, on the photo of “white7” 110376, it would appear that the entire bottom of the rudder is gone! This may be why the wooden tails were not used more, because the wood would shatter where the metal tails would usually just dent, making them more resilient. Again, the fact that a lot of aircraft with metal tails seem to have a flattened "bottom" to the rudder (albeit at an angle, similar to that illustrated by my example above) indicates to me that this is a very real possibility, and indeed may have been a quite common occurance.
Paul