Woodworking

I've recently built a fold out shelf, to dual purpose as a headboard, and I'd like to be able to secure it in the upright position (I think. I'd also consider the down position if it's better somehow) for stability when moving. It's in a camper trailer, so there doesn't need to be any room for movement when it is secured.

Here are some pictures so that you can see better what I'm working with:

vertical position

horizontal position

It is brought out from the wall, so that the window blinds and the top piece on the window blinds are accounted for. It sits against the top piece nicely, but I just wanted to mention this detail because any wall-mounted solution would also likely need to be spaced out from the wall.

I was thinking some type of latch system would probably be the best. Alternatively, I also kind of like the idea of an arm or kickstand type piece that could be mounted to the base piece on the counter and the underside of the shelf, possibly with dowels or something?

Let me know what you guys think.