Looks like I found the answer to the labeling of hats. On their site in the FAQ about labeling (
http://www.cpsc.gov/about/cpsia/faq/103faq.html#hangtags) it says:
"I make socks. Am I required to attach labels to each item?
No. The reasonableness of attaching a label to hosiery has already been thoroughly considered in the application of the federal Care Labeling rules. Those rules can be a guide to what is practicable in this case."
Since hosiery and hats are covered under the same exemption for FTC labeling, it sounds like hats fall into this category as well. So I can put it on my hang tag.