I have been playing my "One" life campaign (no award weapons or legendary status and no using heroes) and finally found a fairly reliable way to beat this level without dying.
Using the AT-AT and as an Engineer, taking the first two command posts are pretty straight forward (as well as destroying the shield generator). I then get close to the third command post in the AT-AT while shooting into it and killing rebel scum as much as possible.
When I see a "chicken walker" come up, I jump out and repair it to full strength. You can then hop in it and force it into the hanger. I then wreak havoc with it, shooting liberally around and to the east of the command post. Once the chicken walker is almost dead, I hop out and run around and take the command post (the reason for doing this is it is CRAWLING with grenade tossing rebels when I first go in).
Then, go destroy the command console. (PET PEEVE: I wish I could tell my fellow soldiers to get the heck out of the way after I lay my DET Pack or stick a grenade to it...I always get at least one or two friendly kills when destroying that thing).
But this is when I completely change the strategy and this works GREAT (at least for me). Instead of going through the tunnel to the last CP, go back out the way of the 3rd CP and go OVER the base (outside) to the back where the rebel transport is. Slide down the side of the back hanger opening, jump in a closed turret in the middle of the open, and take out all the auto-turrets (there's like 6 or 7 of them)--this makes the completing the ending step of this level MUCH easier. Do NOT shoot at the rebels during this time as that attracts their attention and their grenades. [NOTE: one time while going over the top, my AI of the 501st captured the last CP by themselves! I was floored. I just tried running in to get the beacon but all those auto turrets got me on the way to the transport...hence the change in strategy.]
Then, move in along the LEFT side into the hanger, taking note to whack that last annoying turret on the Falcon. The left side helps ensure you are not fighting too many baddies from different directions (keep them all on one side of you). Get to the last CP, run around changing directions a lot while shooting, and capture it.
Then, grab the beacon and zig zag towards the pit under the transport, throwing out healing as needed and shooting anyone in your path. Protect the beacon, but don't stand too near it because they will throw lots of grenades at it (although they don't seem to have much affect)--keep moving at all times so no one gets a bead on you.
I ended up with like 90 kills and 0 deaths.
And that's it! And just with a regular ol' Engineer.
Hope that helps someone.
* SithSpeeder *