Palp event

So ive been scrambling to get my Rebels up high enough to complete this, but sadly, I wont be able to get all my toons to 7* to fully unlock him. That being said im shooting for at least the 6* and want some advice which other 2 toons to try to get to 6 by the event. Also who would you run as lead?

Any advice would be appreciated.

My current squad

The mains:
7* Biggs
5* Wedge (will hit 6 by event)
5* Ackbar (will hit 6 by event)

The question marks:
4* Leia 20/65 towards 5
4* Sthan 5/65 towards 5
4* Lando 1/65
4* Luke 31/65