+1 to the 1 song at a time approach in this situation
on top of the other benefits, this can help save you time by having each player get his instrument/shit together while the other guy is doing his part. as soon as guitars get done, you should be able to unplug, and go right into the bass. as soon as that's done, unplug and go straight into vocals. what you're trying to do is tough, but not impossible.