I don't know about the guitarist, but the bassist would find a 5 string handy, so he could learn the song in closed position and just shift up or down as required.
In Texas, we have a lot of guitarists that play detuned to Eb ala Jimi Hendrix and SRV, especially for blues, I usually keep a detuned bass for those fellows, but a 5 string works better for jam sessions.