I think Garth is cute! I agree, a middle name could open up a host of possibilities. You could also always call your child by whatever middle name you choose, I know lots of people who have family FNs who do that.
I really like Garth.
I'd use Garfunkel as a middle name if anything, family name or not. I teach second grade and we have a Garfield on our grade level. He's constantly ridiculed and that name is much better than Garfunkel. Yikes.