And the pie plate... most of the time those are used on derailleur equipped bikes, but I imagine you could modify one to fit the sturmey. The cog installs like any other coaster brake cog, with the addition of two spacers the cog sits between. Not sure if they originally intended that to be a chainline adjustment, or a more secure method of attaching the cog. I would recommend opening up the hole in the pie plate large enough to sit by the hub flange so it is attached flush to the spokes and rotates with the wheel.
keep the rubber side down!
keep the rubber side down!