What is the overall requirement of your design? Are you looking to use the FastEthernet0/1.310 path as the primary and the FastEthernet0/1.320 for failover? If this is the case, you can track the default route to .225 and use a floating static route for .57 with a higher AD.
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...