I've ran 3 healers each queing on their own, but occasionally they get grouped together, and as long as they don't pick the same squire target (rare) they work out fine. I wouldn't dream of BGing without a plugin like Squire. Not only does running around a path look bot like, but it gets you killed a lot, and yelled at, and when people yell out a name in bg chat for being dumb, you get noticed, and getting noticed is the worst thing a bot can be in a BG. I think the next version of squire you can set the leader by name, so if someone could get the BG bot to que as a party, you could bot 1 DPS and 1 Healer, set the healer's Squire master as the DPS and go at it.
I'm assuming this is because with the wow in game RAF exp bonus, you get bonus exp in BGs? If not, it's better to leave them separate.