Don't worry, it's pretty easy, I 8 box shams in BGs so I have to get round not being able to queue as a raid as well. But, I get constant queue pops using this simple method...

2 groups, queue as group with the leader of each group, sit back and watch the BG pop (i put my mouse over the wow tabs which brings up a preview of each tab)

This way, either both groups get the same one or they don't. No 8 or 7 chars getting it. If one team doesnt get it, leave queue on the team that does and requeue. Repeat til in the BG.

PS: I recommend only doing the 40 man BGs as a 10 boxer