Can't help in Destin, we stay just a little farther east in Panama City Beach at St. Andrews State Park. No problems there in our race car trailer, the state parks don't care what you're driving unlike some of the snooty private campgrounds down there. Nice park, you can get a site right on the bayside, with the beaches a long walk or short ride on the gulfside. I use the reserve america website for florida state parks, they are very accurate on site dimensions, and generally have pics of each site now.
I'm jealous, we can't head south until Nov/Dec., enjoy!