I am a High School Coach. In Kansas there is absolutely no provision regarding body fat or hydration testing. Each wrestler can lose up to 10% of their body weight, which is established before their first practice begins. If a wrestler wants to lose more than 10% an note from a doctor establishing it would not be harmful to the wrestler to lose the weight is required.
I am not 100% sure, but I believe the reason Kansas does not use body fat or hydration testing is expense, and also many of the smaller towns would not have access to it.