We have stayed in many Florida State Parks, though we have not yet stayed at Fort Clinch. I hear it is nice and we hope to stay there sometime. You will find a max length for each site on reserve America. I have yet to see a Florida State park site that will not be manageable for a rig of that max size, though I have seen many sites that would be managable for a larger rig than stated, so in general I'd say they are pretty conservative with their stated max length. Comfortably book any site that is rated for 34 feet (and know likely you would manage a site rated for 32 feet).