Your problem is not in IPTABLES but in NAT and ROUTING. First of all remove the nat from all the interfaces. Both your wireless and ethernet interfaces are using private addresses and NAT is not necessary. You will NAT on the router that has an internet gateway. Then either enable RIP on ZS nodes 1 and 2, so they can exchange routing information, or add static routes about the wireless networks. For example on node 1 add a static route for 192.168.200.0/24 via gw 10.0.0.2 and on node 2 add a static route for 192.168.100.0/24 via gw 10.0.0.1