> Also could I host these on IPv6 and how do Zen do the translation from IPv4 clients.
By the way, this sort of thing can be done. Andrews & Arnold offer an optional (and free) service where customers who are using IPv6, even IPv6-only users, can get their inbound and outbound traffic converted to/from IPv4 by AA's network. So even if you are IPv6-only and have no IPv4 addresses at all, you can still access the IPv4 Internet, and browse IPv4-only websites, for example.
IPv6 only endpoints accessing an IPv4 endpoint requires a NAT64, as I said. Adrian Kennard has a deep philosophical conviction that the Internet should move as quickly as possible to an IPv6 only future, rather than endpoints running "dual stack", so it's no surprise that AAISP run a NAT64 for their customers. I would expect AAISP's NAT64 only to work for AAISP users, not least because of the abuse potential.
IPv4 only endpoints on the Internet at large accessing an IPv6 only endpoint is typically not possible, as there is no guarantee that an IPv4 only endpoint has access to a NAT46 or an IPv6 tunnel. Bearing in mind the original poster was looking for an alternative to multiple public IPv4 addresses, I presume that the usage case was multiple devices accessible from the IPv4 Internet. If so, there is no way to achieve this with IPv6.