In both of these cases, the use of those skins on the current model is acceptable because HTC has stated specifically that they will not be making those other variants. Therefore, any Ju87B can be skinned on the D-3 and any SeaHurri2 on our SeaHurri1.
Other examples are, Ki43I and II on our KI43, 109E-3,4,7 on our 109E, F4F-3 and 4 on our F4F, F6F-3 and 5 on our F6F, FW190A-4,5,6 on our 190A-5. There are many more.
What makes these substitutions acceptable is the similarity of the performance and appearance(same basic engine and weapon configuration) of the real plane to the AH model.
For example, here are a few known subs that wont work.
P-51A on our P-51B
LA-5F on our LA-5FN
B-17F on our B-17G