We were on Odyssey last year for 27 days for a B2B HolyLand / TA and we each brought ONLY a carryon and backpack. We also spent 3 days prior in Italy.
We are D+, so the free bag of laundry each helped with some of the clothes like shorts, workout things, undies and socks, but many of the items we brought - especially all my shirts and my work out clothes - could be washed in the sink and hung to dry in the cabin or on the balcony.
I also bought skirts and a couple of lightweight dresses from Ripskirt that I also washed in the sink in the cabin.