Your mods look good.
You are the skipper, based on fuel and ammo you have to make the decision to return. If you keep sending status messages, the game assumes you want to stay out on patrol and will usually send you on another patrol. Sometimes after you complete a patrol, it may automatically send you on another, but you must decide. You don't get punished for not completing more patrols.
Don't run out of fuel..I assume you've found the icons where you can check fuel milage at current speed, using this you can determine when you need to head home, but don't push your luck.
Don't forget RSRD is historical, sometimes the patrol zone just places you in shipping lanes. Learn your history and you'll find the big convoys and TFs.
On a whim I left Manila at the start of the war and went right to the Bungo ignoring anything. I thought I might be able to get there and catch the Jap Pearl Harbor TF returning and get some payback. It came right on time, 6 carriers with it.
Better to start out of Manila early war as all the action is South. There are several large invasion forces attacking Java Feb and early March 42. The largest convoy of the game can be found Feb 28 N of Semarang, about 60 merchants.
I think I've fought every battle in the game. You'll be amazed at the almost historical perfection of RSRD. The Solomon campaign to me is the best of the game. You have several nice battles, some very large, several invasions forces and non stop action...just got to find it.
This is a great link and works perfectly with RSRD. Take the Guad Canel series in this link. Study the times and locations and pick some good ambush points. For instance the Battle of Coral Sea. If you time it right, you can attack the Shoho invasion group, then hit the battle of Coral Sea, then hurry to Rabual to attack the retreating Port Moresby invasion group.
http://www.historyanimated.com/pacificwaranimated/