I've not got any direct experience of the LP pickups, but I'm a big fan of the two-singles-in-series sound. Adding a 'series switch' to twin-single basses (like a Jazz) is a frequent mod I do
However, your description of the different options is a little confusing to me - or pehraps I'm reading them wrong.
Typically 'series' is more low-end heavy & treble-light than parallel - not so much mid-emphasized. When you mention "Or is that pie in the sky and it'll end up being a middy, muddy, hummy mess?" in your Idea 1, this does not sound (to me) as a natural description of the series sound (i.e. middy & muddy at the same time, sounds strange). If anything, I'd expect the 'muddy' to be more likely from putting pickups closer to the neck.
In general, I quite like putting 2 pickups in the P-ish + one-right-next-to-it (but on the bridge-side). The MTD Super series comes to mind

. I don't recall whether yours is a 4 or a 5-string, but I'm typically not a fan of putting pickups neck-side of the P-position; the basses i've heard with that config tend to more naturally drift in the 'muddy' direction.
So I guess in your descripton the P+MM locations would be my preference. Single-coils or HB/MM shapes should work nicely. From a practical point of view, I like two soapbars side-by-side, since it gives a nice 'ramp-like' playing surface, which I find comfortable. (Again, the MTD Super is a nice example)
If installing two singles, I would be tempted to add a series/parallel switch, but I know that goes against your KISS-idea. Perhaps I'd at least actively try both series & parallel configs, before committing to only one wiring permanently. On some basses, i also like using the series/parallel switch as a natural on-board 'boost' feature, but how well that works might depend on the specific pickups you use.