@henryg 

Hello, sorry to tell you that there is no easy way to move devices between the 2 networks; We need forget the current network and reconnect it to the new wifi; per you said, you can move other devices to the guest network; Meanwhile,  there is no hide SSID option over guest network cause it is aimed to provide internet for guests.

There is no big difference between host network and guest network; both can access internet; while the guest network does not have hide SSID option; and some advanced features are not applied to guest network.

May it help.