I think the choices for such an aircraft will be very limited. Chalk's used to be in service in Florida, but I think they are not around any more, but you could search.
If you can't easily locate an operator (perhaps 'cause there are none), consider searching the FAA aircraft registry for those types - it'll be a short list. From that, you might identify an operator.
There are Twin Otters on floats operating in the Caribbean, which be worth a look.