After giving it a bit of thought, I've decided to try a slightly different variation on a pickup wiring mod I've done before on S-S-S guitars like "original style" Strats or Nashville Teles.

As shown in THIS THREAD, a mod I like very much uses a single DPDT "push-pull" switch to enable you to add the bridge pickup in series with any of the other three pickup combos (middle, middle/neck, or neck). Though all three are useful tones, the one that I like best is the bridge in series with the middle pickup. Why? The adjacent pickups give some partial signal phase cancellation, which is responsible for the characteristic Strat "quack" tone heard at the 2 and 4 positions of the Strat 5-way selector switch. But by running the pickups in series rather than parallel, you get a tone with much more depth and fullness, while still retaining much of that hollow, "quack" sound. I refer to it as "super-quack", and with the exception of the classic Strat neck tone, it's become my favorite pickup setting on S-S-S guitars.

While contemplating this same mod for my Squier CV Strat, it occurred to me that, since I love that quack tonal character so much, why not wire the push-pull switch to add the middle pickup in series to the other two? That way, I'd get two super-quack settings--one corresponding to the 4-position (bridge-middle) of the 5-way switch, and the other to the 2-position (neck-middle), which my original way of wiring the P-P switch doesn't allow. The sacrifice that is made in wiring the switch this way is that you don't get the bridge-neck in series combo, which is kind of a fatter version of the middle pickup switch position on a Tele. You also can't have all 3 pickups active at once, as you can at position 2 on a Strat 5-way when the series P-P switch is engaged. But that's fine by me, since it's the "super-quackers" that I like the best!

I'm waiting for an A250K push-pull pot to arrive to actually do the mod, and will post again when I've completed it. Below is a diagram of how the wiring will be done. In a nutshell, the way it works is this: For a pickup to produce signal, it has to be connected to ground at one end and to the signal output path at the other. Say that you have the bridge pickup selected (position #5) on the 5-way switch. With the push-pull at the "in" position, the signal end of the pickup is connected to the output through the 5-way, and the ground end makes it's connection to ground through the P-P switch. Neither of the other two pickups has the requisite output-to-pickup-to-ground continuity to be active. But if you pull up/engage the P-P switch, the path to ground for the bridge pickup now runs through the middle pickup--i.e. the pickups are connected in series and are both active. Bingo! Super-quack!