[libvirt-users] libvirt and NAT on a system that already has a DHCP server

I'm trying to use virt-manager and qemu/kvm on Arch Linux. The box I'm using is also the router for my house. It runs a kea DHCP server. When I try to start the default NAT network, it can't start dnsmasq because that port is already bound. Is there a way to have it not bind on this interface? I see there is an except-on statement in the dnsmasq.conf, but I can't add lines to that directly, and I didn't see any way to add special options using virsh net-edit default. Thanks.