One can find all weather guns mod from here. (NYGM allows deck gun usage in 11 M/S winds.)
http://www.subsim.com/radioroom/down...do=file&id=391
I haven't played SH4, but they apparently have pilot rescue missions.
One thing to break the monotonousness of SH3's orders is to pick a real life u-boat and then follow the orders that were given to it in real life. The orders can be partly (usually vaguely) reconstructed from BdU's war diary and from U-boatnet's individual boat histories. That is how I once got the orders to mine Bristol channel. I had to navigate to a depth of 25 meters right under the coastal defenses. Another time I had to carry a saboteur team to the North African coast. All done in my imagination of course, but it is a game anyways