I'd give that a try for a day and see how it goes (to make sure she's comfortable enough in there to eat and drink, and that the makeshift cage is secure enough).
Otherwise the shed set up for now, and if she breaks in 2-3 days that should be short enough that you won't need to reintegrate...
As long as she's safe from predators and extreme heat/cold then the enclosure is suitable. Ideally she'd be in line of sight of the other birds at least part time, or else if she's gone too long (some broodies take longer to break than others), she may need to be reintegrated back in as you...