Believe it or not, Balmorhea State Park is outstanding, even in the winter. I too have a pop-up camper (Starcraft 11RT). It is a short drive from Balmorhea to Fort Davis, Prude Ranch, and McDonald. Even in the winter, Balmorhea is great for swimming as the water is a constant 72 degrees. Even in the winter, it can get down right hot in West Texas. The camping is "ok" at Balmorhea, typical TPWD camping with the sites right on top of each other. But, the facilities are great. I've also camped at Davis Mountains SP and it to is good. There is more hiking, etc. to do at Davis Mountains SP. Here are a slew of pics from both.
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ShaneA