I hate them as they're weighted typically for simple compressed music and at an SPL level way below that of a simple unamplifed drum for example, then any form of dynamic live 'input' to the meter mic trips them.
I dislike them and try to avoid them, but have played many gigs with them and managed to keep under the ones set a realistic levels.
Some are set so low that audience applause trips them - the band cannot be held liable for that!
I have on a few occasions managed to strike a deal with venues where we have unwittingly taken a booking not knowing there's a meter.....
I agree that we'll plug some LED lights into the meter circuit, that way, we know if we're 'too loud' by the lights switching off, but won't risk buggering valve amps etc.
Then run a couple of long extension leads from circuits not connected to the meter circuit.
The 'mid week daytime soundcheck' sounds like a flipping shambles and I'd rather bin the booking off than do that - that's unreasonable.
Do they get outsider caterers in the week before to cook them a meal to make sure they can use an oven??!!!