Special Sizes (Extra Large) or Just Special
I’ve found another custom golf shoes maker (who also makes regular shoes and will make trainers into golf shoes or cricket shoes). You can visit the site (bigshoesuk) and read all about the specification which includes details of styles, special fitting for problem feet (e.g. space for bunions), and all the details of sole/in-sole/mid-sole etc, etc.
Rather honestly the site tells you that the golf shoes are not waterproof.
They have large size golf shoes at a good price up to size 18 at http://www.oddball.com