There are decent anchors available for hollow doors such as plastic togglers.To install you drill about a 1/4 in. hole,press two plastic wings together and insert.A larger round surface with a screw hole rest on the outside of the door.I believe you'd want 1/8" (thickness of door lamination).

If you don't want to make a hole in the door, you can get hangers that hook over the top of the door. They are thin and flat, so you can close the door with the hanger in place. They come in metal or plastic. You can find them hardware stores, home improvement warehouse, etc.