Customization of libvirt Network Filters per Virtual Machine


In the deployment i have i am using 802.1Q VNETS. I need to deploy a Virtual Router ( i ma testing several solutions), but i have a general concern in all the cases:
As OpenNebula default Netfilter is “Cleantraffic” avoinding IP Spoofng, MAC Spoofing, etc… I want to keep this clean an sane configuration for all the Virtual Machines, except for the instances for Virtual Router .
If i keep “Clean Traffic” Netfilter, there is no possibility to assign to the Public interface a Virtual IP, as IP Soppfing filter will not allow traffic for this IP.

So, i am wondering how can i assign a customized Netfilter only for the instances of the Virtual Router. As i have several network (2 Public and 12 internal) i don’t know in advance the networks that i am going to use for the instance in Virtual Router: I don’t know in advance the NICs and so i cannot preassign in the template the rule per NIC…
==>Is there a way to automate this without preparing a template with all the possible NICs and then use in each instance some of them??

Thanks in advance