I have heard a lot of yacking about extension rings and nobody has come up with a real reason that you couldn't gang a dozen together. Just watch your conductor length. You still need 6" at the edge of the last ring. In the ceiling of the great room of the Ca-D-Zan there are a buttload of 3" rings to get them from the box in the structural ceiling down to the finish of the antique mohogany ceiling we couldn't touch.
