I have to agree with Rocky and Setboy. It is actually something I intend to do in the next year or so. Also make it free for anyone to use (the Baron sounds like the kind of guy that would want his permission to use his), and contant your families geanological society (or just geanology enthusiasts with your name on Ancestry.com) and let them know about both tartans (and the Baron's claim to be head of the family). You may get enough interest to get a cheap run of the tartan (like the X-mark run) and thus establish that your tartan is the "family" one and the other is just for posers.

Adam