Contact a PASA or IKO certified instructor to see about obtaining Level III certification. Some instructors may offer a "moss back" certification program for experienced riders much as was done in SCUBA diving decades ago with the onset of certification in that sport.
A list of certified kiteboarding instructors and schools worldwide for PASA and IKO appear at:
http://www.pasakiteboarding.org/
http://www.ikorg.com
Some of the certified PASA and IKO instructors in Miami include:
Miami Kiteboarding, Inc.
Christophe Ribot
305-345-9974
www.miamikiteboarding.com
Sky Banditz International, Inc.
Francisco Escudero
305-947-8454
skybanditz.com
There are quite a few others in Florida and elsewhere. Please check the PASA and IKO directories for more.
Certification and manditory safety gear requirements have started at Crandon, other areas may not be that far behind.