Access to the local subnet from the WAN interface (NAT RULE?)

Hello everyone!

I have 2 SOPHOS firewalls in two different buildings, connected by Long Range Aerials (point to point).

FIREWALL 1 is configured like this:

LAN  192.168.122.X         (Aerial 1 is part of this DHCP pool)

WAN  public IPs  (static)

then FIREWALL 2 is configured like this:

LAN 192.168.111.X 

WAN 192.168.122.X     (DHCP from FIREWALL1 LAN ZONE) 

I need to grant access to the subnet 192.168.111.X  by all the devices connected to the Firewall 1 LAN ZONE 192.168.122.X.

Which one is the best practice for this situation? At the moment i granted a RDP access to a specific host in the LAN 111  by using a NAT RULE.

But what if i need to access the whole subnet instead of a specific host?

Thank you in advance.

Matteo