As soon as I saw this title I asked myself: why are you not running an empire team? I say this because palp and Shore are the two most difficult to obtain and arguably most crucial parts to said team. If I were you, I would stop running rebels and start running EP (L), Vader, TFP, Shore, RG/B2/SF.
I run this team every day in arena, and can constantly rank top 10. Heck yesterday I even beat a full gear 11 team of EP, Vader, Boba, Baze, Shore to rank number 1, all as FTP (my opponent was a whale). If there are lots of shores on your shard, simply replace RG with b2 or SF, because any enemy AoE will likely cause said characters to dispell the enemy shore taunt.