I’d start with a search for “unistrut” tracks as these are pretty standard across multiple industries and applications, which makes them cheap, then add “wheel trolly”.

One track down each side 4 trolleys per board and make each board two and a bit feet long and you can have 3 down there. Attach them together with some webbing and a couple of snap fasteners, so you can pull each board out and remove it or just let it dangle down the wall.