Note, you'll need to manually set the TCP/IP address for the second adapter (which we'll be using as an ssh proxy): "Using DHCP with manual address".
I couldn't get this to automatically grab DHCP information from an Airport Extreme, even setting address reservations with DHCP client ids. I left the address reservation in the Airport Extreme (so no other adapter on the network would grab it), but it would've been nice to be automatic.
I also set the primary wifi adapter to "Using DHCP with manual address" because apparently without it, the bonjour service reports the secondary wifi adapter, which screws up your standard ssh, since the secondary is proxied to stash.