Most of these gigs are throw-and-go and the environments tend to be a bit noisy. I would not rely on instrument mics or SBTs. A good quality sound hole pick up or a UST through a quality pre-amp represent, in my view, your two best options. Both have advantages, both have short comings, all well documented here on the AGF over the years. I have, and have used all of the above. Today I never use an instrument mic, rarely use my SBT guitar, keep the sound hole pickup in my bag as a reserve and go with the UST/pre-amp combination.