I would think it would be a lot easier to get a large inflatable tube and lay it across the path of the jet so the pilot could see it and more easily judge the impact point (or yes, sandbags, foam, or whatever). Yes, the pilot did a good job with the stool, but why a stool that the pilot can’t see in the first place? Just saying.
A few feet away from the intakes, and a few more feet away from downward vectored exhausts. Why do you think they might not elect to use a big inflatable tube?