Two options come to mind. The simplest would be a lug or two. The little things which are sometimes used to secure flyscreens on windows.
The item shown would need filing down, then it/they could be mounted on the of the holes next to the door. Get your friction right using a locknut then twist (still using pliers) to open.
The other suggestion would be using an over-centre spring setup, which is probably more complex than it needs to be.