It's a Texas State Park, you can stay 2 weeks. Don't know the rates.
The rates vary depending on whether you stay in the (very cool!) adobe cabins, or get a campsite with only water, or a campsite with water and electricity, or a campsite with water, electric, and sewer. No matter what, its very affordable. Check the website https://tpwd.texas.gov
Yes you can stay overnight and you have to call them for the rates.
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