There used to be a place in Seattle that would take your original tube type wheels, and use the center and weld them into new tubeless rims. I had some 18" widowmakers done back in the late 80s, they used my centers, and welded them into 19.5 rims. That might be an option, taking a set if 20" wheels, using the centers, and welding them into 22.5 rims. I am assuming the liability for a shop, using old parts, is going to be an issue though.
