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?
use a heavy rubber bladder material. fill it with water. tie it down so it can’t move, whatever. But, make sure the pilot can see each end. Anything is better than a little stool the pilot can’t see in the first place. you know those bladders used to raise things off the bottom of the ocean? lots of other options that our tax dollars could come up with other than a stool.