Rust on the anchors not important and normal for that age. Should be resprayed with something to delay further rust and improve cosmetics. It is very likely to rust through.
The anchor points themselves though should be inspected closely. On a BF, these are weldments with the tang you see hanging down through a slot in the fiberglass. Inside the tang is welded to a large backing plate, this sits on plywood to spread the load to the structure. It is possible for a long term leak to have rotted the plywood backing, then you have a structural problem. A tell tale sign of current problems is water dripping from the tang. Water ingress at the tang point is very unlikely as it is under the overhang and water runs downhill, but if very wet it will run out there. Tightening the turnbuckles may cause some drips as it squeezes the plywood like a sponge.
A leak anywhere along the side penetrations can pool on the top side of that overhang and rot the plywood. It is hard to access this for inspection, but you can see some of it by removing all the drawers and looking inside with a good flashlight. Feel around back there (being careful not to cut hands on screw points etc) for moisture. The area may be carpeted and the carpet will retain moisture. Also look for signs of mold or staining. Typical entrance points for water are the locker doors along the side for batteries, propane, refer, etc.
