Oh I see yeah addons are in host most. Nice.
As for the ranges over VLANs. You want a /64 per vlan really. Since you have dhcp, maybe not. But in my case, with a mikrotik router, it doesn't do dhcp on ipv6 to hosts, only to other routers.
So I have to use RADVD / IPV6->ND. This mean, each host configure their own ip address.
1x ipv6 ip using EUI-64, which uses the mac address with the /64 prefix.
1x ipv6 that is anonymous and change with reboots.
Also, a /64 doesn't end at ::7d1 but you more than welcome to limit it to that if you want, but its actually a whole lot more.
For example, fd00::/64
Start at fd00:0000:0000:0000:0000:0000:0000:0000
ends at fd00:0000:0000:0000:ffff:ffff:ffff:ffff
With this example, you can see a network card's mac address fits in there. Although it goes through the EUI-64 algorithm which changes it slightly.
I use fd00 to keep a static range across my home network, and all internal traffic use this range. I don't nat it either to go out publicly. Each device also sets up my ISPs prefix. The OS then use the public ip for internet and the fd00 for private stuff. That also allows me a much stricter firewall rules for the internet vs lan between my vlans.