We don't have the luxury of contracts much less with riders. If we pulled a stunt like that we'd be ditched permanently. This ain't the big time. It sounds like you think all your customers are major acts.
After my Shuttle shut down in protect mode twice I started metering the AC prior to plugging in and the last two times the Shuttle shut down the AC had metered fine. There doesn't seem to be a way to predict if the AC will fluctuate out of the amp's tolerance.
Just curious, did you ever serve time playing bass in "bar" bands?
This is interesting to me as I am a college bar player myself. If you test it and it meters fine, could it change once you apply a huge loud to it post metering? How often is this problem for others? I play some divish bars around Denver-Boulder and never had a problem, though this maybe why my SVT-7 kept pooping out on me.
For example: meter it with no load, but while playing you got 2 guitar amps, the 9.0, a PA, mixer. several FX strings....
Again, not at all trying to be snarky here, I'm NOT an electrical engineer and I am honestly curious if a good metered source can be insufficient once a bands worth of current is pulled.
Perhaps fine un-loaded can be far from fine loaded? Please, correct me experts.