In the meantime, thinking about the controls again. I'm confident I can 4 four pots in the control cavity with all the wiring - which means I can still do 2 vol and 2 tone.
However, the issue becomes the knobs.
Speed knobs look nice, but I think they'd be annoying that close together:
The plan for this axe is black hardware, so black dome knobs (going unused from one of my bass kits) would suit and leaves a bit more room between the knobs:
That's some options, so reckon I'll be drilling the two extra holes equally spaced - after the grain filler probably.