I've got a sub gig coming with a horn band and it's fun material but because of the horns about half the set list is in keys like Ab, Eb and Bb. I only have 4-string basses. So do you think my best option would be: 1) Buckle down and learn the whole show with one bass in standard tuning (and just live without the low Eb's), OR 2) Tune my 2nd bass down a half step, learn those tunes as if they were standard tuning and just switch to the detuned bass for the flatted key songs? And not to complicate things further, but the leader of this particular band doesn't always follow the setlist exactly so I won't be exactly sure when or how often I'd need to switch bases till we're actually live. Thanks in advance.