You must knock down the defense ships with torpedoes first. Or at least scatter the group. Only thing they can do against torpedo is run the hell away from it.
Don't fear active sonar that much, if you turn toward the pinging platform and stay on the border of your torpedo range, they shouldn't be able to detect you.
The Akula could complicate things. If you could knock it first (or again, at least make it solve torpedo evasion instead of your solution), it would be all easier.
Don't bother with TASMs .. those are good only for unarmed ships or standalone ships. They have no change against formed group.
Harpoons are a bit better, but not really much.
By firing missiles you only expose yourself. However you can save them for killing ships which are already damaged.
Yeah .. that mission is tough. I don't remember if I ever done it, but I for sure tried many times
