It is possible to write data beyond leadout already with the MMC commands in RAW DAO 96 writing mode. It's just that no program has implemented this. I'm thinking to include this into my tool, but I'm not sure of the best way how to include it, i.e. as part of the main sector image file or as a totally separate extra image file.
But alexnoe is right, we need to know what data is inside of that ring. Once we know and it's just normal data written in the normal way then it should be no problem copying the Saturn CDs.