Would it be easier to sew large "hems" in each side and slide the board through? You could have a couple made up and just swap them out. Metal bar instead of wood would be cleaner and they would not want to roost on them, if that's a worry. Sorry, just my brain running off at my mouth.
This is exactly what I plan on doing. I haven't decided if I want to use wooden dowels or emt conduit. I know I have some conduit left over from another project, if its long enough, I'll use that. I plan on putting up some brackets like in a closet for it to rest on (like this).