What a view for so little cost! The Florida Keys have unequaled beauty (in the US) with their shallow ocean water and brilliant turquoise color it produces—all without needing a flight to get there. You can easily drive it all.
Staying in the Keys is generally a bit pricey, as are most waterfront places anywhere, but if you camp—whether tent or RV—you can have it all for approximately $30/night, complete with the ocean mere feet from your site.
Every site in Long Key State Park is direct oceanfront, with adequate space and shade to provide some privacy as well. The least private side is actually the beach...but this is not a crowded place... so you don't have hordes passing in front of you.
In the winter—midweek—this is mostly filled with retirees enjoying their winter break. We joined them and had a great, quiet time of sun and relaxation. The boys played on the beach and enjoyed themselves thoroughly in the warm Key air—the water was off limits due to an abundance of Man O War, but they waded some carefully. Without the Man O War, swimming and snorkeling are possible here—meaning, of course, we'll have to go back to see what they are like! Some people had inflatable boats with them that they used, and many folks fished from shore.
We took advantage of a free ranger-guided "Learn to Kayak" course that was enjoyable—and had the wind not been up the next day, we'd have traversed the "canoe trail" that is here. Instead, we walked the Golden Orb Trail and enjoyed learning about the different mangrove trees and local flora and fauna.
The biggest plus to this campground is the view—second to very few as far as campgrounds go. They also have very nice bathhouses complete with hot showers, picnic tables, ground grills, and each site has its own electric and water. The park was very quiet from the patrons—there's not even much wave noise here due to the reefs breaking the waves well off-shore.
The only downside I can think of is the road traffic noise. The Overseas Highway is right next to the sites, so you hear every car or truck that passes—at all hours—without the wave noise to drown them out. However, I would never let that stop us from staying here. The view and the general sense of peace and quiet far outweigh some basic traffic noise for us. This is one place we REALLY hated to leave.