How to give access to guest network to machines on the main LAN with an Airport Extreme? I have an Airport Extreme Base Station with two networks: my main network and a guest network. Is it possible to set it up so that devices on the main network have access to devices on the guest network, but not the contrary?

I would like to give access to some devices to people on my guest network, so the easiest way is to have these devices connected to the guest network. However, my devices on my private network do not have access to devices on the guest network, and this is not what I want. I guess I could add routes to all devices on my private network to fix that, but I was hoping there would be an easier solution by setting this up on the Airport Extreme.
According to this article, it is not possible. All devices on the guest network can only see the Internet and nothing else. Two devices on the guest network cannot even see each other.