Caballo Lake State Park has several campgrounds that aren’t represented on the Dyrt app map. We tent camped at the Riverside campground below the dam over Easter 2014. See my screenshot of the park map. Google map has 100s of reviews of this campground. It was ok. Kind of crowded and the Rio Grande flowed shallow and muddy (unlike in Del Rio, Texas, from where we had recently moved, where the river is beautiful, above and below Amistad Dam). Alas, at least it was nice to be outdoors.