routed tap devices

I am using kvm-82 on a 64-bit host and giving my virtual machines routed tap devices and utilizing proxy arp to provide them connectivity.

My host has two ethernet adapters, one connected to the WAN and the other is a private link to another server with a private IP address.

Even though I'm assigning device names (on the host) based upon mac address, it seems that depending upon the order in which the linux kernel sees my ethernet adapters they are behaving differently in terms of ip forwarding.

If I run ip link I see eth1 listed before eth0 and a virtual machine running behind a tap device that is using ip forwarding sees eth1's IP as it's first hop in a traceroute.

If I swap eth0 and eth1 (via their configuration), the first hop in the guest's traceroute is eth0's IP and ip link shows eth0 first. Is there a way to control this behavior other than switching physical ethernet adapters?

I may be paranoid, but I don't want the virtual machines to "see" my private IP address when using standard tools such as traceroute.

Anyone have any ideas?