BGLeader goes to the leader of the largest group with the earliest creation date. So if 2 5 man groups join and leader A started his account 1 sept 06 and leader B started 2 July 07, leader A will be the leader of the BG no matter what rank, or name his character has. Typically large groups use enabler, to reduce queue times so odds are if you use "join as group" you will be leader. If not there are several player frame addons that can always show just your characters, or you could pull out their tabs from the raid tab. I bet if we bug the creator of Jamba enough he could add casting bars to the already existent HP bars on his UI and you'd be golden no matter what