My suggestion would be to use a different brand of t-shirt
All the other t-shirt brands I've seen have a SEPARATE size/care instructions tag and a separate brand tag (Hanes, AltAp, AA, M &O, etc).
I'd just use a brand that has a separate brand/size tag to make things a lot easier.
Although I could be saying that because I'm no big fan of Gildan (although many people are
)