Let me first of all post following informations:
The "Panzerfähre" (Dragon kit No. 6625 or No. 6669 as well as HobbyBoss equivalents) don't show any rudder. That's incorrect. These vehicles used a rudder otherwise the crew wouldn't be able to steer the vehicles in water. My knowledge is based on original-photos showing this item.
More information will be printed in the German modeling magazine MODELL FAN later on in the year.
The publisher doesn't allow to preview any details prior the magazine will be printed and available. Therefore I will give more information when published.
Everyone, please be patient until later on.