Book Bahia Honda State Park before anything else in the Keys, and let the rest of the week fall around the nights you get. Its campground sits on Big Pine Key with pads a few steps off the water, and the swimming is what people drive down for. Hold those nights, then rent the van against them, because on these islands the campsite is the scarce half of the trip. From Key Largo it is a hundred miles or so of two-lane highway and bridges to get there, so plan on sleeping your way down instead of running it in a day.
Bahia Honda State Park on Big Pine Key
Give this park two days if the calendar allows it. Sandspur beach faces open water on the Atlantic side, the old railroad bridge stands off the end of the park, and a day here is snorkel gear, a kayak and not much planning.
Which loop you book decides whether the van fits, and Florida State Parks publishes the limits loop by loop, as of August 2026. Sandspur takes rigs up to 23 feet hitch to bumper and the turns into the sites are tight. Buttonwood, sites 1 to 48, has electric and water and the park's dump station, and it handles longer vehicles site by site. Bayside, sites 73 to 80, has no electric and sits behind a bridge with 6 feet 8 inches of clearance, which rules out most high-top vans.
If your van is longer than 23 feet, Sandspur is out and Buttonwood is the loop to ask for, which is also where RV rentals for the Keys end up.
When Bahia Honda has nothing on your dates, Long Key and Curry Hammock are the other state park campgrounds on the highway, both with water on at least one side of the road. Neither is the beach that Bahia Honda is, and people book them to be in the middle Keys rather than for the swimming.
Key West is a day out from here, not a base. There is no state park campground in town, so you drive down, walk Duval Street, stay for the sunset and come back to the site you already paid for.
John Pennekamp Coral Reef State Park in Key Largo
Take Pennekamp on the way in if you get the van late in the day. It is the first Keys state park off the mainland, the reef sits offshore, and the snorkel and dive boats leave from the park's own basin, so the morning starts with a walk to the dock instead of another hour of driving.
Everglades and Biscayne runs belong to Miami, and the rest of the state is on the Florida campervan hub.