Would this template feature solve your "each network has its own network address" problem?
MX/Z1 - Firewall Rules and DHCP Reservations for Templates
You have additional source and destination options when configuring layer 3 firewall rules for a configuration template. Because the subnet for a given VLAN may be different in each template child network, VLAN objects allow you to create firewall rules using the VLAN names as source and destination network objects, rather than actual IPs or CIDR subnets. These VLAN objects are automatically translated by each child network into the local subnet associated with that VLAN.
If you wish to use only a certain IP within a VLAN in a firewall rule, you can add a host bit. For instance, let us imagine that you have a firewall rule containing the source Data.50 representing the Data VLAN, host bit 50. If a child network has subnet 192.168.100.0/24 for the Data VLAN, this source will be interpreted in this network as 192.168.100.50.
Mousing over the VLAN dropdown when entering a Source or Destination will display a hover list of available VLANs and their addressing.
DHCP reservations can be configured in much the same way. The VLAN name for each DHCP scope will be autopopulated, and only the host bits of the reserved range needs to be set.
Source:
https://documentation.meraki.com/zGeneral_Administration/Templates_and_Config_Sync/Managing_Multiple...