Kissimmee Prairie Preserve appears above, an excellent amateur astronomer friendly Florida dark sky site (not in Kissimmee) image by Jason W. Higley

CLICK IMAGE TO GO TO JONATHAN TOMSHINE'S DARK SKY FINDER

This image is a composite assembled from data acquired by the NASA/NOAA Suomi NPP satellite in April and October 2012. 
CLICK IMAGE OR HERE TO SEE BIG ORIGINAL VERSION

Some Known Florida Amateur Astronomy Locations:

Area 51 (near mile marker 51) Map - also see Astronomical Society of the Palm Beaches website for details or consider checking with someone at South Florida Amateur Astronomers Association to see if/when they are going out there.

Chiefland Astronomy Village - see their star parties!

Fakahatchee Strand Reserve (a.k.a. 'The Fack'), off I-75 - touch base with someone at Everglades Astronomical Society to see when they're out there or see their calendar.

Farrout Observatory, Dade City, FL "Where Tampa's Astronomers Cluster"

Kirby Storter Roadside Park - It's surrounded by the pristine Big Cypress Preserve.  Here's a google maps link that shows it clearly too.  See this 'street view' to see the site!!!  Looks like it's free too.

Kissimmee Prairie Preserve -not in Kissimmee, is has astro observing sites too, check with them for info here at this link http://www.floridastateparks.org/kissimmeeprairie/

Osceola National Forest site of NEFAS (open to all)

Shiloh Site at Canaveral National Seashore (used by Brevard Astronomical Society)

Shired Island in Dixie FL

Spanish Harbor Key - Site of the Winter Star Party

Withlacoochee River Park (county park with fees) - see http://www.stpeteastronomyclub.org/viewing.php for more info.