Well, i belive this mission is set up so your wingman is invunerable. Not sure about hard setting.
The first 2 parts of the mission are fairly easy. But before you go to the convoy, make sure your wingman hypers out first.
there are 2 Assualt Shuttles. One will target your wingman as its first choice, the other will go after you.
So it boils down to 1 ATR you ahve to worry about. The big problem about A/S is they ahve turrets, and they are murder against a slow moving target.
The one method i was able to take 'em out was in Medium. What i did was make sure my shileds were at 200% (both sides) angled the shields back, then attack the A/S with lasers and Ions... head on. As i got closer i would wait until my secondary shields were getting hit, then i switch them to double forward (you should now have 200% in front again) keep firing those lasers, and at the last second right after he turns away (imperials were never good at playing chicken) dead-fire 2 torps. he should be destroyed if you laser/ion fire was accurate.
Granted, i did this out of sheer flustration one day, and my ship was badly chewed up, but at least i was able to complete the mission.
hope it helps somewhat