So you only care about the logical ordering of the columns. It seems trivial then to add a column mapping layer in the metadata to map the user-defined apparen

So you only care about the logical ordering of the columns. It seems trivial then to add a column mapping layer in the metadata to map the user-defined apparent order to the physical order so that select * would return the order you want. In relational algebra the ordering of the rows and the ordering of the columns are undefined. It's up to the database to arrange it in the best way possible. The ordering of rows and columns is specified when queried.