According to this article, I can set my "guest" network to NAT mode: Use Meraki DHCP to have the guests on a 10.0.0.0/8 network and still permit them access to the wired LAN network if the SSID firewall settings permit. However, if I allow access to the Local LAN through the SSID firewall settings, will this only apply to the printers on the Local LAN or everything in the Local LAN?
Preferably use bridge mode unless you have no other choice.
Preferably have printers on their own VLAN so you can allow traffic via the MR firewall and traffic shaping configuration of the guest SSID. If this is not possible you can still have fixed IP's on your printers or just allow TCP to the ports used by printers.
The easiest and simple way to do it would be to create a NAT mode SSID with Meraki DHCP and then create firewalls rules on the Meraki AP's to only permit access to the specified LAN IPs of the Printers.
Below are two KB articles that will assist you with the configuration;