That’s a good call, a couple of Vintage Jazzes and Precisions (plus Les Paul’s & Teles for our 6 string brethren) wouldn’t cost too much but would save the day, and even on a fiver per rehearsal pay for themselves pretty quickly.
On track with the original question, I’d go for the cheapest rounds and flats as they'd only be to get through a rehearsal. I’m pretty sure everyone would change to s new set of their favoured brand once getting home so no need to get expensive or loads of ranges, just steel & nickel rounds, plus flats, standard gauges.