Question About Creek Crossing

How clear was the testimony that Allen and the girls crossed the creek AFTER the van drove by?

The private drive runs along the high edge of a pretty steep ridge. Its lowest point is just north of where it goes under the High Bridge, then it goes uphill to the house. If you went “down the hill” and crossed the private drive, then walked along the bottom of that ridge, hugging the bottom of it, you would not see or be seen by a car driving to the Weber house.

But in the middle of February, with leaves down, you could easily see/be seen while crossing the creek or from either bank of the creek.

It makes more sense to me that they went down the hill at 2:13, and crossed the private drive at 2:14/2:15, crossed the flat and then the creek by 2:20-2:21, Libby’s phone stops moving, the creep starts to play out a sex fantasy at the point of a gun, the van drives by interrupting, the murders and clean up/covering of the bodies occurs, and the perp walks out.