TM gain and AOE is your friend here. If you have the right team this is a breeze. I used HK, 88, 86, B2, and Palp all gear 11. I think the Ewoks took maybe 5 turns in the bonus tier (the two elders in 1 round used most of those). I don't have much speed on my droids.
Using a Vader lead probably isn't ideal because you don't get TM gain. For some people it's not so much as not having a team geared enough, but just not having the right characters to be able to take out the heavy hitting ewoks before they get a single turn.