I love the external cam too! I even did what you're doing and added back in the umark.tga to my Grey Wolves install.
However, after finding out how much an IX boat costs with renoun, I've turned off my ext cam for that extra 15% renown.
One more patrol and I can afford it!!
By the way, when you upgrade your boat, do you keep your crew and any upgrades? I didn't notice when I got my trusty U-50 VIIB.