Leading Edge Profile is the Culprit
I'm slow-building my wings and I've just gotten to the step where I'm installing the landing light lenses. As others have mentioned, I too have a gap at the leading edge no matter how hard I push from the inside. I made sure to orient the lenses correctly, i.e. there is definitely a right side up, but I think I understand now why the lenses don't fit better-it's the shape of the wingskin leading edge. At least it is on my wing. A closer look reveals that the radius of the skin leading edge is tighter than that on the lenses (and the ribs for that matter). I don't know about the rest of you, but when building my outboard leading edges I had to push pretty hard to get the ribs far enough forward to get the rivet holes to line up with those in the skin. The same phenomena is happening with the lense where the leading edge skin has a tighter radius, therefore the lense will not fit tight up against the inside of the skin. Picture trying to get the curve of a baseball flush with the curve of a golf ball; it simply won't fit flush.
I've already done all the trimming so the next step is to match drill the holes for the backing plates. I think I'm going to ask someone to help with this step so that one can drill and the other can hold the lense against the leading edge as hard as possible, but I know there will still be a gap. There is no way around it if the radii of the leading edge and lense are different.
Empennage Complete Except for Tips