If they are being the edge routers, coming in from the ISP, can you create a VLAN, with a public network range of the ISP, and assign that to the outside interface?
It would make it a whole lot easier. Personally, you can run in to allll sorts of problems, if you have to double NAT etc, and do all kinds of weirdness.
For instance, I worked at a company, we will call CompanyX once, who had one ISP, and behind the ISP was a switch, with a VLAN that was carved, with a L2 vlan, and from a port on that switch (with the ISP VLAN) to the public outside interface on the ASA.
Sorry if this sounds confusing, and feel free to ask anymore questions. I'm usually busy during the day, but I try my best to respond to posts.
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...