First: Try you're Rumble 30. Does it work? Ask the director after rehearsal.
Second:
Since you have a good past with the Fender Rumble 30, how about getting a Fender Rumble 200? The 200 Watts into a 15" speaker will be plenty loud and full for that big band, and you'll even have options for a second cab. It's only 34lbs to carry too.
Keep in mind, when playing with acoustic bands, even loud ones, you don't need the power to match the entire band together, just be able to be a bit louder than other individual acoustic instruments on stage. Bands like that are used to listening to each other and matching volume. As long as you have the power to support the trumpets in the higher register, you are good. When the rest of the band is at their loudest it is very normal that they cover up the bass, piano and guitar... then they will come down in volume and let the rhythm section re-assert and take over.
Issue with my 30 is that it has no DI out - so it's a no-go for FOH supported gigs.
My Rumble is from the first gen, I'm not sure how the later ranges compare, if anyone can shed some light it'd be great, as I love consistency.