> They vary in plausibility and ingenuity.

There I agree.

> There is no more suspension of disbelief needed here than with a hundred other ballads, to my mind anyway.

That's where I disagree. The girl certainly needs to pull a cunning trick of some sort, unless someone else is coming to the rescue as in some of the continental variants. But what villain would fall for "turn your back so you don't see me naked", when he would see her anyway when he pushes her into the water? Or "Go and find a sickle to cut those nettles". Does he really believe that she will refuse to walk through some stinging nettles but submit to being drowned?