Not sure how you could queue without opening the window.
I typically queue as a group, so only one toon has to open the window.

All of my toons have this on a bind:

/script AcceptBattlefieldPort(1,1)
/script LeaveBattlefield()

When I have the window open, saying the battlefield is ready, one press and they join.
Until I've finished loading the BG, I can spam away with impunity for others to join without leaving.

At the end, with the score sheet up, the same macro has me leave.