To paint over ANY surface, without sanding, use a product called ‘ESP Easy Surface Prep’, available at hardware and paint shops. Wipe on, wipe off and paint in 90 minutes. Works well over enamel paint , without having to sand. SAVES HOURS of work.
I like this DIY headboard. Easy to have the board cut to the right size at Home Depot, almost as easy to cover as the kitchen chairs. Wouldn't even have to mount it to the frame, could just mount some D-rings to the back and hang it from the wall on either side of the window like a picture frame.