You won’t get much benefit from closely spaced receivers. Ideally you need receivers surrounding the aircraft. It will work to some degree if the aircraft is “outside” the receivers, but not nearly as well. The problem with having a cluster of receivers that are close together is that, for anything other than an aircraft right on top of them, they all see about the same message arrival time, so multilateration doesn’t have much to work with; the differences in timing are so small that measurement errors drown it out.
