If it is only for the one gig which you are not miking instruments, I'd say use two condensers halfway across the room you're playing in. You'll get some crowd noise, but if your instruments are cutting through like they should you will hear them just fine. Also, if it is for the band only, try miking everything at a practice session and record using the RCA's on your board. This way you can hear and correct your mistakes before your actual show.