How to get a Time Capsule to actually work in IPv6 without wireless

I have an unusual home configuration, in that I have a routed network.  If you don’t know what this means, stop reading now as you are wasting your time.  While the Apple Time Capsule advertises IPv6 capability, getting it working is rather difficult.  To start with, if you do not use the wireless capability of the device, the controls are really non-obvious.  For another, the Time Capsule appears to ignore the default route capability in routing advertisements.  Hence a manual configuration is required:

Time Capsule Configuration

Looking to the left, one must select “Router” from the IPv6 mode and not “Host” as one might logically expect.  Then, because RAs are not being handled properly, one must manually enter the default route (the long way).

Finally, because you are supposed to be routing, you need to enter some address for the “LAN” side.  My prefix is 2001:8a8:1006::/48.  Note I’ve dedicated a bogus network ::8/64  to the effort.  All of this allows me to do what should have happened automatically; not your typical Apple Plug-N-Play style, is it?  For a company that claims to be IPv6 Ready, I’d say Apple still has a ways to go.  Sadly, they’re better than most.