We had a factory-built rotary mower on the farm around 1960 that we used to cut down cornstalks with a Farmall H. It came with a metal shield that mounted behind the operator to protect from flying debris. It left a hole maybe a foot by two feet between the back of the tractor deck and the bottom of the shield, so we hung a gunny sack there to catch what tried to come through it. I remember that sack wore out pretty quickly and had to be replaced often. You knew it when something got through.
I'd think being out in the open like in this photo would be a real pain, literally.