Well, I wouldn't limit her sodium intake until the last days before show and then I would reload sodium the day before show, without sodium she'll appear flat.
Aldactone is a mild diuretic and for a female contestant I would go for a dose in between 25-75mgs a day, take it all at once in the morning. Of course you should watch out for your potassium and sodium levels despite aldactone being a mild diuretic. A week on aldactone will suffice imo.