Yeah, that mission is pretty tough! I found the best way to beat it (and continue on the winning path) is to do the following- for the convoys, initially focus on trying to find and destroy Stingray clusters as fast as you can (preferably saving missiles/stormfire ammunition for the defense of the space station). When you hit the station nav point, go balls out- lock the burners, burn past the station, target a red manta, tell your wingmen to attack it, target another red manta, unload a couple missiles / stormfire him to death (I prefer the Banshee for this mission, and if you're good, you can take out a red manta in a single pass if you're willing to use missiles), target the next red manta, track him down, and repeat. You'll probably want to unlock your burners once you break into the first wave of Red Mantas. Oh, BTW, the station sucks at shooting down torps- so you'll probably want to try to shoot them down yourself with the stormfire gun if you see any get launched and you are in a position to do something about it (e.g. you're within gun range of a red manta when it launches)
Some things to keep in mind that might make it a little easier-
If a Red Manta gets its torpedo off, ignore that particular Manta until all of the other anti-capship elements are engaged/destroyed. They only have one torpedo a piece, and will focus on space superiority instead of capship attack (at least, that's how it appears to me) once they've dropped the torp.
IIRC, you reload several times in this mission. Conserve your ammo for the space station defense- but once you are defending the station, use all your ammo and don't be stingy on the burners! You'll get reloaded after each station nav point involving station defense.
The biggest threat to the convoys seem to be the stingray clusters. There are Red Manta, and they can do damage, but the transports usually do a pretty decent job of shooting down torps. The transports can't shoot down plasma rounds from clusters though, which is why you have to be on the look out for stingray clusters.
To summarize, it's a very difficult mission to successfully complete, but it's doable. It took me a couple tries, and usually the station would have only one antenna left at the end of the mission (in otherwords, one more torpedo hit would have = no more station), but keep at it and you'll get it. Oh yeah, and don't worry about the convoys too much, I think the successful defense of them only boosts your mission score, but doesn't effect whether you "successfully" complete the mission or not. (That's contingent upon the the survival of the space station)