So what about a ‘personalized’ or customized tag?
Make is a tailor skill+1 on to what it already takes.
IE you can make the item already, but your mutated, so you need modifications to make it fit better. So thus, you spend a few hours reworking it (add like 50% of the base materials in or something) or make it specifically fit you.
If your HUGE and you need a backpack, you would just make it bigger or strap that sucker to your thigh, or belt, like a fanny pack 
Then it can only be worn by the creator of the personalized item. Done