After a few mid-air collisions, we worked out a permanent place to stand and alleys where we dash for the mic and then back out quickly. This is only necessary for an instrumental break, because the voices are all picked up by just leaning toward the center, and whoever is singing lead stands in the middle.

It was pretty tricky at first, but now it's what we're used to. I heartily recommend getting away from the morass of wires and mics and going with a simpler approach, and it gives the audience something visual as well as audio during the performance.