Trigger Maru Overhauled 2.5 for Silent Hunter v1.5 maybe?...
TMO is a difficulty mod, and as such can be difficult, especially if you set the rest of the game to "Hard". If you are seen by ~one~ airplane, they do the E.T. trick and fone home. They tell all their buddies where you are, your heading and your speed. From there-on out, you will be dogged by airplanes, including zeroes with impossible bomb load-outs... Similar happens when you are seen by a Sampan or fishing boat. Don't be seen. Only felt...
If you're wanting to do something between Stock and TMO, try
Webster's Game Fixes Only, which is the stock game with a lot of the nigglies' rough edges smoothed by Webster, or you could try TMOwTw, which is
Trigger Maru Overhauled with Training wheels, by Dave Grayson. I like them both. Much easier to deal with quite a few aspects of the game with the tweaks those gentlemen did. There is also
Ralles RealModPack for TMO_RSRDC_OTC by Bleiente, and it's a new mix of TMO with Run Silent Run Deep, with some of Bleiente's tweaks. For me, a person almost ~has~ to use
MultiSH4 v1.5...