It seems I am not alone in thinking it is wise to embed database table column information in the PHP class that will interface with that table. Harry Fuecks, in his blog entry titled A Development Infrastructure for PHP, points to work by Tony Marston.
Check out Tony's notes about his business class field properties and compare with the DB_Table schema setup documentation. They are obviously very similar, at least in example and documentation. The both do automated validation as well, and have "hints" for form-building embedded in the class.
Nice to know someone is on the same path as me (although Tony is obviously **much** further ahead :-).