Someone mentioned this in another thread (relating to turning the Tide as horde in AV),
and it is just brilliant. So simple and effective - I can't believe I didn't think about it.

When defending or capping the bunkers (won't work in the towers) , place your guys opposite each other, in a north south east west arrangement.

Facing towards the stairs. I've had my guys on top of each other, which means that pallies and warriors have a field day in the confined space on my team. (thunderstorm doesn't knock them far and they are straight back on me.)

The above formation should ensure that you have coverage of each other and 3 can be dpsing or healing the 4th.

Can't wait to try this out.