Thinking in hanging a swing from a covered area at the back of our garage. See photos attached. The swing would go parallel to the main bean, attached with screw eyes, between the column at the middle and the doors at the back. It is a small swing - 49in wide. Wondering if the structure is sound for this. My worry is not so much the beam, but the columns. They are just 4x4s and seem to be standing on the concrete, no ground anchoring! Not sure if it is enough for this... Thank you in advance!