In an emergency you could get a nail and put it thru the hole and then bend it so it doesn't come loose But my experience is that I have never had a snap up bracket come loose once the chains have been attached and the bracket closed.
Carry a pair of wire cutters and extra nails You should be able to find those pins at any camper store
2004 Jay Feather 25E
2001 Ford Expedition 4X4 EB 5.4 3.55 rear
2004 Ford Expedition 4X4 EB 5.4 3.73 rear