The water is already moving at Village Creek's campground, a free-flowing creek under sand-pine and hardwood on the edge of the Big Thicket, a rare thing in Texas. The canoe launch is at the sites, so a paddle and the overnight share the same woods. You float under the trees and come back to the same loop.
The Kirby Nature Trail starts as a boardwalk through dense thicket and runs on toward carnivorous-plant bogs and cypress sloughs. The preserve's wider trail network spreads through units that include Turkey Creek and Hickory Creek Savannah. You walk those as a day from the campground and still sleep on the creek.
Camping in Big Thicket National Preserve is limited to the backcountry on a free permit from the visitor center, and the preserve has no campgrounds, so the van stays at Village Creek State Park. Kountze is the town on that side of the thicket.
The hookup loop takes a travel trailer plus a tent, and a hike-in primitive area sits off the loop if you want to walk in for the night. A campervan fits that electric pad. If you need more sleeping space, look at RVs for rent in Beaumont.
Village Creek often reaches capacity and recommends reserving camping and day use, especially from February through September. A day in the park without a campsite still needs a day-use reservation. Book the overnight first, then the van.
Sea Rim State Park
The Gambusia Nature Trail Boardwalk crosses open marsh and comes out on the Gulf beach at Sea Rim State Park. You start in grass and water, then the boardwalk sets you on sand with the Gulf in front of you. From that shoreline you beachcomb, paddle, swim, and fish. Birds work the marsh along the same walk.
Sea Rim's campsite page lists electric sites on the Piping Plover loop, next to the beach access and the dune boardwalk, and that loop is the one you can reserve. West Beach primitive drive-up sites are first-come and can close in extreme high tides or other weather. Hurricane season can close those beach sites, so reserve the electric loop if you need a pad you can count on.
Port Arthur shares this coast. Lake Charles is the next Gulf town, and the rest of that run is campervan rentals in Louisiana.
Martin Dies Jr. State Park
The Neches and the Angelina meet in B.A. Steinhagen Lake. Martin Dies Jr. State Park is on that shore, with bald cypress standing in the water and a paddle trail that crosses sloughs, both rivers, and the lake. You can swim and fish from the same bank, or walk and bike the trails, then come back to a lakeside site. Jasper is the town for this park.
Camping is mostly water and electric sites, many next to the lake or a slough, and this is the second night when Village Creek is full. West of Beaumont, Houston is the next Texas city with its own trip.