On our trip across the country, we discovered Landry Vineyards through Harvest Hosts. But it does appear, according to Jeff & Libby Landry, this large winery and event venue allows others to camp their RV / Trailer overnight.
We arrived during a winter storm with heavy rainfall. Usually, they have you park in a field next to the vineyards, which has awesome views. But due to rain, the mud was so bad there was a chance of us getting stuck, so they had us park for the night on a concrete parking area next to the tasting room.
This is dry camping. So there is no water, electric or sewage available. There are restrooms you can use while the winery is open 11am - 5:30pm Monday through Saturday. But they do allow campers overnight on Sundays, too, even if the winery is closed.
I would suggest hitting it when it's open. They have 24 different wines ranging from dry to sweet, reds, ports, whites, fizzies and some hybrids made with blueberries and blackberries. Tasting is free with the purchase of one bottle of wine per person. The petite syrah, red zin and chocolate raspberry port are worth the trip on their own. Rare to have such good wines coming from a small southern winery.
The setting is peaceful, quiet and safe. The owners even turned on the lights and allowed us to use the covered outdoor patio next to the tasting room since the weather was so bad. They can accommodate any size rig and have 6 spots available. Call at least 1 day in advance. And, since it's free...be sure to thank them by making a purchase in the tasting room.
The drive from the highway is only about 6 miles, but the roads in are tight and windy with 30mph curves, narrow and bumpy roads. Not too bad, but be slow and careful through here.