To make sure all subnets can communicate with each other, you need to setup routing at each gateway which will be your new routers. Static routes will work, but with 8 nodes in a full mesh it is better that you setup a spanning tree algorithm like EIGRP or RIP.
Cisco’s DHCP Helper can help you reduce the amount of DHCP servers you need, but to simplify things, you should setup a separate DHCP server at each site. That will also make each site more independant in case the WAN connection fails.
Example DHCP scheme:
Scope 192.168.0.2 – 192.168.0.30
DNS <DC IP Address>
Scope 192.168.0.34 – 192.168.0.62
DNS <DC IP Address> (Same as Site A)
Example Static IP Route:
Site A to Site B
IP Route 192.168.0.32 255.255.255.224 192.168.0.33(OR name of Network Interface)
Site B to Site A
IP Route 192.168.0.0 255.255.255.224 192.168.0.1(OR name of Network Interface)
This is a light overview of what needs to be done, so post any questions in the discussion section.