My method of dealing with pesky Destroyers
 

When I encounter a target rich convoy and am sighted before I'm ready to commence operations. I will head on to the bearing the destroy coming at me, submerge and stop all engines once I'm facing a head on bow shot. I'll then select salvo, pick a spread of 1.5 degree, pick two tubes with the same type torpedoes sometimes 3. Wait until range is a little more than 2,000 yards then fire. Almost always at least one torp will hit and a lot of times both or all 3 before the destroyer takes evasive action. I feel it's a waste of a torpedo or 2 but I'm not complaining on being alive. This in Dark Waters, not sure if all mods give you the salvo option.

you could also use the acoustic torpedoes, fired either from the bow or the stern.
the problem with the acoustic-jobs is that you cannot direct them to specific targets, other than if they are approaching from very diverse angles. and yet....if you fire more than one at a time they there is a good chance they will detect and home-in on the same target, for better or worse.

Indeed when it gets that late in the war I will use acoustics for the same purpose singly.