All my suggestions fail to line up with at least one of your criteria, but I thought I'd throw them out here anyway. Only suggesting shows I've actually done myself.
Someone has already mentioned ...Gamma Rays... which has five girls but isn't a comedy, though it does have some moments. It's not a one-act, but it is relatively short.
There's an allegorical one-act called Lepers that we've had a lot of success with. Five girls. But not a comedy.
One of my favorite shows is The Real Queen of Hearts Ain't Even Pretty, which is both hilarious and meaningful, but has only four girls (maybe one can stage manage?) and isn't a one-act but can be cut down if necessary.
You might not be able to use these, but maybe they'll point you in a direction...? Break a leg!