If I was in real fear of this, I don't think I would dehydrate myself rather than risk rape. I think I would have a group of us go to the latrine together. (I know. That's what we always do!) I don't know if soldiers keep their weapons with them all the time, but I don't think anyone would risk raping a group of armed women.
If that wasn't practical, I'd find a safe alternative, like a home-made bedpan. These women have had training... it simply doesn't make sense.
I am on a forum with a lot of army moms and NEVER has this been mentioned! There are a good number of women soldiers represented on the board...of course the media will never make her prove her allegations...