Not much to add, other than don't give up experimenting! There will be huge amounts of bass/contrasting frequencies in such a big band and I can only imagine how difficult it is setting up and sound checking so many people! I use a home made Gamma Pad (isolating stand) or a Markbass Markstand, and they make a big difference when playing on old hollow wooden stages. Not sure if mentioned, so I apologise if so, but where is your amp in relation to where you stand on stage, and have you tried EQ rather than the filters? Try cutting bass a touch to begin with and see if that makes a difference, maybe borrow a graphic EQ and experiment with cutting exact frequencies. Good luck.
Edit: just a thought, are you sure it is YOU that sounds muddy? Could it be that the band is that big that the whole sound needs work? It might not be your sound directly but someone else, or a combination of drum turnings, guitars or something else.
And, have you tried other basses? I use Markbass gear and moved my Jazz on as I didn't like the two together. For my purposes a Musicman Stingray, and now mostly a Precision sound much better.