I have an odd approach to this mission that... might not work well for everyone.
I had a thread about this mission a while back, I can dig it up if necessary - this mission is indeed, a real pain. My bomber of coice for the operation is, surprisingly, the Ursa. As such, playing with your power system is key in getting the operation to be a successful one. Your load-out should of course consist of the Helios torpedo, as well as a bank of Maxims - I prefer mounting these on the chin turret myself. You are of course free to allocate any other banks to weapons you feel appropriate, but YOU NEED THOSE TWO WEAPON SYSTEMS!
As a further word of advice, that bank of Trebs isn't going to help you - the Sath is famous for its GOODNESS AWFUL turret hitboxes, so, lobbing long-range missiles at the flack guns isn't going to save you from their barrage...
...Which is why you brought the Maxim. The next part of your assault is amongst the most harrowing - when the Sath arrives (assuming you've been role-playing, and have not already charged out into position...), put full power to engines and target the flack batteries. Make sure your maxims are armed, and get ready to dump all power to guns - removing those flack turrets makes your life a hell-of-a-lot dangerous. Once in rage, open a barrage until the flack screen is no more - dump all power back to engines and target the first beam turret assembly. Tell ALL of your squadmates to attack a different beam, but on the same side as your assualt - telling all of them to do this is critical, as they're remarkably stupid. Redundancy in numbers.
Attacking the Sath's beams is always going to be obnoxious, as again, the hitbox is awful. On the other hand, it does add a degree of skill which you must employ to be successful. Make sure you give yourself plenty of room during an attack run, as your bomber is slow, so is the Helios lock, and that Sath is damn
fast. Spacing is vital during such an attack run. I can't tell you how many times I've been frustrated by sighting down a turret for... far too long and not even having the bloody torpedo lock. Don't let that happen to you.
If you and the Orestes survive this initial whomping, it's just a matter now of staying alive, really.Getting away from the scene may actually be your best bet, as (a.) huge chunks of debris moving at ludicrous speed are bad for your health when the Sath blows, (b.) huge shockwaves are bad for your health when the Sath blows, and (c.) huge swarms of fightes from the Sath also really blow as well.
In short, this mission is all about local emplacement of weapon systems and situational awareness - sure, every FS mission is like that, but not every one takes a Sath to bring it out.