Texas defines indecent exposure in Texas Penal Code § 21.08 as follows:
§ 21.08. INDECENT EXPOSURE.
(a) A person commits an offense if he exposes his anus or any part of his genitals with intent to arouse or gratify the sexual desire of any person, and he is reckless about whether another is present who will be offended or alarmed by his act.
(b) An offense under this section is a Class B misdemeanor.
As you can see from the above, when you expose yourself, you must (1) have intent to gratify the sexual desire of another person, and (2) be reckless about whether another person is present will be offended or alarmed.
I'll assume (1) really would not apply.
And given the circumstances you described of the distances and sight lines, it does not appear that you would be reckless in whether your neighbor would be offended or alarmed. I think that as long as you are somewhat discreet in your skinny-dipping I don't think someone would be successful in bringing charges against you for indecent exposure.
Of course it is always a possibility that the neighbors would complain to the local police, but I don't think a criminal prosecution against you would be successful given the circumstances.
You should however check your local regulations regarding fencing. Most jurisdictions have some sort of fencing requirement for pools for safety reasons.