I think the transparency in the P-38G might be hampered by the modelling in AH of using the "gunsight dark glass," which was in the real-life P-38G to be used only optionally at pilot's discretion in bright sunlight. In AH, the use of this extra layer of glass in the way of the gunsight reduces transparency, making it very hard to see through the gunsight compared to many other aircraft in AH, even other versions of the P-38.
From the P-38 manual, this is the layout for the gunsight of early P-38's:
where the manual says "When flying in bright sunlight, place the dark glass in position over the gunsight. Later airplanes are not equiped with gunsight dark glass." The gunsight dark glass was stowed in a holder at the left side of the cockpit when not in use.
From the P-38G cockpit in Aces High:
It seems that the gunsight dark glass is permanently installed. Given that we can't toggle such a feature, I think that it would be better if it were permanently not installed for visibility in the Aces High environment.