I've got the exact same issue. The solution when I investigated was to use IPv6 network prefix translation; however most routers do not support it (including M

I've got the exact same issue. The solution when I investigated was to use IPv6 network prefix translation; however most routers do not support it (including Mikrotik routerOS, which is what I mostly use). So lacking that, instead I've gotten my own AS and am now a 'proper' internet peer.