CARP and MAC Address Spoofing?

[Hektor]

Hello,

I have 2 servers and 2 public IPs (1 IP for each server). I want to configure HA via CARP and pfsync.

LAN CARP interface is up and running via Virtual IP.

As far as my understanding goes:
I need a 3rd public IP for the WAN CARP interface, don't I?

Maybe it's possible to use 2 different IPs from another network on the 2 existing WAN interfaces and use 1 of the public IPs on the CARP interface? Problem is that the provider is using MAC address filtering so I would need to spoof the MAC address on the WAN CARP interface.

Any suggestions how to accomplish that?