Think about it, most of the weight will be on the roll bar between the risers. The frames themselves that support the fabric are plenty strong enough too. The only issue I see is her rear end will be planted firmly on the fabric, that would be my only concern, just put something sturdy over the fabric and supported by the frames that hold the fabric. Also she will have a small rear anyway to fit between the risers. See picture below, support the circle area.
