Add dummy xen network interface to AppVM

I need to use software in my AppVM with licensing that check for network adapter MAC address.
If I add add net qube to my AppVM and change the eth0 MAC address then I can work with this software.
I don’t want to have network in this AppVM but if I set net qube to ‘none’ then there won’t be eth0 device in AppVM.
I’ve tried to use dummy interface:

ip link add eth0 type dummy

But the software won’t recognize it and seems to be looking for networking device in /sys/devices.
I can create offline networking qube and use it as net qube for my AppVM but I don’t want to use unnecessary RAM for this dummy net qube.
I’m not familiar with Xen but I’ve tried to edit my AppVM xen xml config and manually add network interface in template:
cp /etc/libvirt/libxl/myappvm.xml /etc/qubes/templates/libvirt/xen/by-name/.

    <interface type='ethernet'>
      <mac address='xx:xx:xx:xx:xx:xx'/>
      <ip address='10.137.0.xxx' family='ipv4'/>
      <script path='vif-route'/>
    </interface>

But libxenlight fail to start with this config:

libxl: libxl_exec.c:117:libxl_report_child_exitstatus: /etc/xen/scripts/vif-route online [76889] exited with error status 1
libxl: libxl_device.c:1302:device_hotplug_child_death_cb: script: /etc/xen/scripts/vif-route failed; error detected.
libxl: libxl_create.c:1904:domcreate_attach_devices: Domain 33:unable to add vif devices
libxl: libxl_exec.c:117:libxl_report_child_exitstatus: /etc/xen/scripts/vif-route offline [76938] exited with error status 1
libxl: libxl_device.c:1302:device_hotplug_child_death_cb: script: /etc/xen/scripts/vif-route failed; error detected.

So my question is how can I add network interface to AppVM in Qubes?

UPD:
Also tried to add different devices <interface type="network"> as described here:

    <interface type='network'>
      <source network='default'/>
    </interface>

and

    <interface type='network'>
      <source network='default'/>
      <target dev='vnet1'/>
      <model type='ne2k_pci'/>
    </interface>

But I’m getting different error:

Start failed: Failed to connect socket to '/var/run/libvirt/virtnetworkd-sock': No such file or directory, see /var/log/libvirt/libxl/libxl-driver.log for details

I’ve ended up doing it like this in dom0:

sudo mkdir /etc/libvirt/hooks/
sudo nano /etc/libvirt/hooks/libxl

Paste this script inside:

#!/bin/bash
guest_name="$1"
libvirt_operation="$2"
timeout=60

if [ "$guest_name" = "myvmname" ] && [ "$libvirt_operation" = "started" ]; then
    (
        exec 0</dev/null
        exec 1>/dev/null
        exec 2>/dev/null
        for i in $(seq 1 $timeout);
        do
            if qvm-ls --running $guest_name | grep -q Running; then
                xl network-attach $guest_name mac=xx:xx:xx:xx:xx:xx
                break
            fi
            sleep 1
        done
    ) & disown
fi

Then add execute permission:

sudo chmod +x /etc/libvirt/hooks/libxl

Reboot.