There are some van taxis that should hold 5. They aren't as plentiful as regular cabs, but you should be able to get one. Everyone wants them cuz there is more room. Last year we saw one coming and waved at him before he even got up to the loading area and he montioned for us to come get in as soon as he got near. The transfer from Carnival to the airport is 15pp.
I hope this helps,