I've always just ran my overflow through the inner fender. When I teched in for the GG autocross, they told me I had to have a catch can, so I sucked down a Mtn Dew as fast as I could, then used a mini-bungee cord to tie the can to the bumber bracket under the fender.
He said as long as it didn't fall off, it would be fine. It stayed on there, too.
I'm thinking of having a custom one made to fit under the inner fender, so it's out of the way, but more than likely mount one under the battery tray.