Adding Perch Content to Email Subject Line

Can anyone let me know if there is the option of adding the value from a <perch:input> tag into "Forms -> Form Options -> "Email subject line"?

I have a client who wants to manage a list of recipients themselves and have the Subject Line populated with the chosen recipient in a form, but I don't see any way of being able to interface with the subject line in a more dynamic way.

Thanks in advance!

That's brilliant Drew, thanks for that! It worked exactly as you outlined.