I got KiOgon to make me a rotary switch for my bass with a single, passive MM pickup (basically the same as yours @stewblack) that switches through four positions, single bridge coil, both coils parallel, both coils series, single neck coil. So I have volume, tone and the rotary switch.
As @Dad3353 says, think of the pickup as a pair of single coils mounted next to each other.