Well, at G8 a zeta on Kanan with your best mods ensures victory....barring that chopper is best 5th with speed/health/protection on him. Zeb needs potency, potency, and more potency. Zeb also needs to be called for the assists....ALWAYS.
Kanan needs health mods and a little potency. Try to keep offense down on thrawn. Ezra needs cc/cd/speed. Hera needs speed/cc/cd. Give Hera and ezra as much protection secondaries as possible without sacrificing maximum damage as they are your damage dealers.
TAKE OUT THE DEATH TROOPERS 1st. This cannot be repeated enough. They will wreck you time and time again.
With all of my advice you may get lucky and beat it on try 1-5 at G8....but be prepared to try for hours and hours.