Back to 3 Stars. You actually get 4 minutes to complete Mission 28, 29, and 30 so there's plenty of time to get 3 Stars.
Campaign Echoes of the Force 28 (3 Stars)http://youtu.be/kIYX3G6Uk-I
Campaign Echoes of the Force 29 (3 Stars)http://youtu.be/jHMMf2mMYNE
Campaign Echoes of the Force 30 (3 Stars)http://youtu.be/s_XD5OVhlBU
The difficulty with Missions 30 is primarily due to Darth Vader, who does area damage of nearly 10,000 per second.
Getting 1 Star should be doable for most if you start by working on all the perimeter buildings then targeting down just a couple of interior buildings before Vader gets to you. I got 1 Star on my first try but not sure if I can get beyond 2 Stars at level 6.
If you're at level 8, I think you still need to spread out your infantry to buy time. In my video, you'll see I tried to lure Vader out with my initial troop drops but he didn't bite. Then after Vader emerged, my troop positions were poor and they wasted time targeting down the walls instead of Vader. With proper positions, I think this missions should be very doable.
Good luck and let me know how you do.