G'day mate. I recently bought a cheap strat copy and looking to mod the wiring too. I've looked at the Dan Armstrong wiring option, 7 way wiring and also the 2 volume 1 tone option. There are some good YouTube videos by Breja Toneworks that give step by step wiring tutorials and several options. This one looks interesting:
Unless you go for really powerful singles, or a really weak humbucker, or a really powerful humbucker, there are always going to be balancing problems with HSS guitars.
Standard humbucker and powerful singles means that the pickup outputs are going to be much better matched. The downside is that it's not going to sound that much like a Strat and that the tapped humbucker single coil sound is going to be thin and weak compared to the powerful middle and neck singles. So you may then not want a tapped humbucker sound on its own, but instead just have it tapped for the bridge and mid together sound.
A low powered humbucker is still going to sound thicker than standard single coils, but a lot of the original PAF style humbuckers, especially if slightly underwound, with Alnico 2 or 3 magnets, produce a pretty clean, less mid-focussed sound that sonically is a lot closer to the singles. Slightly overwound singles will help to bridge the output gap whilst keeping most of a Strat vibe for the mid and neck position. Again, a tapped humbucker sound can be pretty thin, especially on a low output pup, so a parallel wiring option for the humbucker may be better than a tap.
A really powerful humbucker may seem an odd choice, but when tapped, it will have a thicker more powerful single coil sound that will balance well with the single coils.
Other options are something like an SD P-Rails in the bridge position, with single coil, P90 and humbucker sounds available. Very versatile pickup and allows you to get good matches with the mid and neck pickups for clean and semi-clean sounds, whilst still packing a hefty humbucker punch for when things get dirty. Or a single-coil sized humbucker in the bridge position, that will give a brighter and more focussed humbucker sound that sits better with single coils.
It's probably easier to start with your ambitions for the guitar in what you want it to sound like or do and then work back from that.
I did fit a Strat with a JB Jr (B), duckbucker (M) and Little '59 (N) (all SD pups) as a sort of experiment. No taps, just standard Strat combinations. OK for rock, and sounded OK but not outstanding for clean. Mid pickup was OK, mixed positions not that inspiring. But I did miss having a standard Strat neck pickup as it's such a lovely sound.