Implementing IP6 in 8.3

[freebsd-net]

Greetings,
 I'm evaluating an ISP for the sake of building BSD operating systems on hardware
that they use (DSL modems, in this case). When I had my old NEC server, I had a
MIPS environment to develop in. I managed a 28k kernel. In any case, I'm back at
it for use in alot of hardware I have laying around. In my current situation, I'm
using a ZYXEL Q1000Z modem to connect to their service. While it's a relatively
new modem, it doesn't support IP6. It is my hope to replace the OS with one that
does. :)
I leased a /48 of IP4's from them, which /also/ came with as many IP6's.
So, not having implemented IP6 on any of my boxes (except by way of tunnel brokers),
I'm wondering 2 things:
If my underlying OS (FreeBSD-8.3) can support IP6, will it still function, even tho
my gateway (modem) doesn't?
Am I /correctly/ attempting to use it?
I'm answering authoritatively for the many domains I own. They have all functioned
well for many years via IP4. I have added the requisite AAAA records in all the zones,
as well as the associated RR's.
While the gateway (modem) /does/ have an IP6 address, I can't "speak" for it out of
DNS, because it would be an "out of zone" record. Even tho I'm the RP for the /48.
So it's up to the modem to answer accordingly.
BUT, I'm not sure I'm initiating any of this correctly via rc(8). Or more specifically,
via rc.conf(5). While I've read as much as I can find on the topic related to BSD,
boot messages indicate at least -- "IP6 gateway unreachable".
I'm currently using:
rc.conf(5):
ipv6_ifconfig_re0="2602:00d1:b4d6:e100:0000:0000:0000:0000"
ipv6_defaultrouter="2602:00d1:b4d6:e600:0000:0000:0000:0000"
I also have the corresponding host IP in hosts(5).

Any help, pointers, guidance, answers /greatly/ appreciated.

Thank you for all your time, and consideration.

--Chris