Token suggestion. Unistrut has relatively cheap rolling trolleys of different sorts for different configurations. The channel can be special ordered curved. Search for differing dimensions. For recovering wall space, build an interior 'pocket wall for the door or store it externally, straight barn door style or curved. You could also adapt the uni strut angle as a top or frame material. Most common components available in galvanized in the electrical aisle of your local box store. Order specialty stuff from a supplier. Chain operating garage door opener might manage the load cheaply. Image search for unistrut trolley and unistrut curved. You may find other purposes such as a lightweight rolling overhead lift. Use within specs.