There were some REALLY old posts a while back asking for the 109E7 because it had drop tanks, and was identical to the 109E4.
Well it was NOT identical. It was, in fact, an advanced version
But that's not important. From what I understand, MANY E-4s were upgraded in the field to allow drop tanks to be mounted, as WELL as a single bomb. I'm thinking of trop variants, and the Akrika Corps, etc.
Well, AH has the 109E4 with the centerline bomb mount, BUT we don't have a drop tank for it. Well the Default E-4 didn't even have a bomb mount! It had to be added. Since we have one WITH it added, just give us a drop tank for it!
Very little code involved with that, I would think. Simply designate where the tank is. How much it holds, release points (if those are even coded), and then factor weight into the COG, add a hint of drag, and you're all set!