Xaviere Guitars

[Hemisaurus]

Seems like phantom power would save me from having to route out a separate cavity or do any drilling. I am concerned about the amount of internal space an SG has to offer, but it seems like the drawback would be that I'd have to run any additional effects through an effects loop, which seems to kinda castrate stomp boxes.

You can run the phantom power box in front of the effects, in fact on a pedal board would be ideal, you could power it from your pedal power source, that way the effects would see the signal from the guitar.

The rule of thumb, for FX loops is, modulation effects are good in one (phase/chorus/delay/tremolo/eq) but boosts/distortions/fuzz and the like should be before the amp. As in all rules, your mileage may vary. I've used a delay before a fuzz for interesting effects.