It would be better if you put her in a screen cage.
Panthers need the ventilation.
Besides, she cant dig a tunnel in dry sand, it just wont work, and she could get herself buried or become egg bound if you do it when she shows signs of digging.
drinking more than normal, not really a sign of gravid, but she could just be thirsty, or its too hot in her cage.
what is her basking temp?