I'm working (when I happen to have time) on something slightly more comprehensive: the mobile hotspot.
self.exec_cmd('ifconfig ' + self.wlanif + ' ' + self.network + '1 netmask 255.255.255.0 up')
iptables is small (400k deb) but I don't think there isn't any reason why it couldn't be optified.
In theory even the modules could be installed outside the rootfs but that's asking for trouble.