Thank You for the suggestion, Gil.
However, I think the taped-over guns flush with wing l.e. cannot be discarded altogether, as this was indeed how the early P-40D/Es were delivered to the front:
source: The Hawk's Nest
source: Replica In Scale
This drawing also suggests that the guns (and shell ejector chutes) were covered with tape:
source: Wings Palette
Regards,
Aleksandar