You could do that, using the Strat switches in place of the rotaries I suggested above. Connect the 4 pickup tapped outputs to the switched terminals and leave one position empty for OFF. This makes it possible to turn the whole guitar off, intentionally or not. There's going to be some major interactions between pickups, like if you have one selected for a 5k tap and another for 20k...whether in parallel or series. Might not sound so good.for example, i had hoped that instead of a row of dpdt switcches for on off, it would be a row of 5 position strat switches for off, on, and the various voices.
Also have you considered just how you're going to manage all those taps when putting pickups in series or reversing phase? If you just sit down and begin to sketch this out you'll come to see the sheer enormity of this idea. This isn't electronic theory, it's just a matter of connecting & disconnecting lines together. But it's your own idea, make the effort to figure it out yourself.
and then hopefully a single on off for series parallel.
For 3 pickups??? Trust me, it doesn't work like that.