I have a trusty five-string BaCH Rickenbacker -style bass that I have modified with Music Man -style Seymour Duncan SMB-5D pickup on the bridge position with series/single/parallel (ON-ON-ON) toggle switch and I would like to add another SMB-5D pickup on the neck position with same kind of toggle switch (series/single and parallel). In addition, each of these pickups have/will have their own volume controls. 
The question is; how can I make a switch that would allow me to change the middle position single coil -setting of the toggle switches to be able to switch between inner and outer coils of the SMB-5D pickups but still managing the possibility of switching to series and parallel, what ever the position of the "inner-outer coil" -selection switch is.
I tried to figure this myself and tried to google comparable wiring schematics but I am afraid that I am rather noob when it comes to planning wiring schematics and also I suck at searching so I tried asking here if anyone can help.
Also I would like to have an honest opinion; is this inner/outer coil selection switch worth the hassle, does it even make a noticeable difference when changing from outer to inner coils?

The question is; how can I make a switch that would allow me to change the middle position single coil -setting of the toggle switches to be able to switch between inner and outer coils of the SMB-5D pickups but still managing the possibility of switching to series and parallel, what ever the position of the "inner-outer coil" -selection switch is.
I tried to figure this myself and tried to google comparable wiring schematics but I am afraid that I am rather noob when it comes to planning wiring schematics and also I suck at searching so I tried asking here if anyone can help.
Also I would like to have an honest opinion; is this inner/outer coil selection switch worth the hassle, does it even make a noticeable difference when changing from outer to inner coils?