Are you really sure about the small wing bulges on Hartmann's aircraft? I think I'm able to discern the bigger oblong bulges on the wing in the photograph you provided, just inside of the wing Balken-cross...
Only the first Erla built planes had the small ones because they used up spare wing they had in stock before converting to the new style.
And I'd think the Luftwaffe would probably supply its Ace of Aces with the best it could get - and since the bigger wheel well bulges have a much better drag coefficient, methinks they would have provided him with those...
I could be wrong of course, but I don't think so.
