Yes! And there is no extra charge.
Yes you can
A few weeks ago I saw tents with RVs on the same site.
Most Texas state parks allow tents at the RV site and even have a pad form to go on but I'm not sure about Possum Kingdom
I've done it before at other Texas State parks with family friends that have an RV without a problem. Usually campsites are limited to how many people you have and not the number of tents.
You need to ask them by calling. They may charge extra for that.
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