That is pretty much cheating and if you are playing with out duds then the mk.14 is better than the mk.23 anyway the 23 is merely a 14 with only high speed setting and 4,500yd range.
What you should do is get a few mk.18s and do the same trick they are wakeless.But dont get rid of every mk.14 or mk.23 you want some higher speed fish as well.
Or you could go into your careers file and simply give yourself 50,000 renown but that is pure evil cheating and makes you a scallywag. And dont ask me how to do that renown thing I wont promote that level of cheating you will have to figure it out yourself.
Another "cheat" you can use is have two careers at very diffrent points in the war like 1944 and 1441(ha ha you will have a Gato when the others have galions!Take that Ponce De Lion!) then have both of them in the "office" in port load up the 1944 career and then from the office load up the 1941 career sometimes the 1944 upgrades will carry over and be aviable in the 1941 career including torpedos. It does not alwyas work though so you have to try a few times.I mention that one because it does not help you all that much.The adding renown cheat is getting credit for ships that you never sank.Earing the renown properly is a way to inspire you to become a better skipper.
I am sure some know of all three tricks but it dosent matter I bet they have not be mentioned in a while.