I'm in the same situation. We have one large network and need to break it down into smaller networks. We have an access control list to create in Meraki that will block communication between classroom VLANs, but it will go well over the 128 limit. Our next option is to break up the network into several networks. I wished we could use network objects in the ACL's and that would solve our problem, so we could combine multiple CIDRs in one object.
The base network settings I can clone, but the switch's port configuration gets wiped. I need a way to copy a switch's port configs and restore it to the same switch in a different network. The Python scripts sound promising but I'm only finding a script that copies the port config back to the same switch and network. We may be able to use the script and move the port configs.
Any luck on figuring this? This is a feature that Meraki really needs to add. We have over 50 switches to move and that's a lot of work reconfigure all the switch ports.