TrueNAS Scale 24.10.0 with privoxyvpn app

I created a new install of 24.10.0 and I used an ix-app custom app to create a docker container with the binhex privoxyvpn image.

To get it working I had to set the container in privileged mode and the container works fine and connects to vpn, but I am struggling to route other apps through this container.

Usually I would create a docker network like container:privoxyvpn and then I would set the network for the other apps to be this network.

But I can’t see a way to set the network in the custom app to be this new network I created.

If I manually change it using portainer then every time I stop and start the app again the network is reset back to the default one.

Is the solution here using YAML instead? Has anyone managed to do this?
Or… am I going about this the wrong way and with TrueNAS I should be using a different approach or app to get my apps routing through a VPN?