that one should not go in the bog with the others, because it does not need a winter dormancy.
As you view the bog, imagine you have a front and a back.
the front will be the side you view the bog from the most.
Put the Judith Hindle in the back, since it grows the tallest.
Put the S. purpurea dead-center, where it can form a nice rosette.
Put the Binata on one side, right or left.
put one VFT on the other side, and the 2nd VFT right in the front.
For a 12" bog, I wouldnt worry about drain plugs at all.
instead look for one of those large and tall plastic "saucers"..
the same plastic saucers everyone used for "the tray method",
but larger and with higher sides..then you can keep the water level halfway up the bog or better..