Sister has had to fly the Florida-Cuba charters a few time for work, and her business group is the only people on the plane trying to not haul half a Costco back to the island-based relatives. You can apparently get away with five carry-ons for many of those flights, provided everything is appropriately weighed at check-in. (Charter company needs to know how much baggage they've got to shift to a second cargo-only plane that's effectively tethered to the primary passenger flight.)