Firewall/NAT

Hi Guys, Im just looking for a little help please. I am a bit confused about the "best practice" for my network. As a background, I am running a HyperV Server which has 2 Physical NICs. Monowall is running fine on HyperV at the moment. I am also hosting 2 SBS2008 servers on the host. I can run both SBS servers on the same interface in monowall using a hyperv virtual switch, or I can use them on seperate interfaces by simply setting up more virtual switches.

I currently have a /30 subnet routed to my DSL IP. The DSL IP is not in the same subnet.

DSL IP: 203.59.162.xxx
Routed Subnet: 203.59.75.xxx/30 (4 IPs, 2 Usable)

My monowall has 4 NICs, 1 WAN which has the DSL modem exclusively which is bridged to a physical NIC, 1 LAN which then bridged to a physical NIC (which connects to a switch + AP), and 2 optional interfaces which connect to virtual switches in hyperv (each server connects to their own virutal switch)

So from this arrangement I currently have it setup so that Each Usable IP address is listed in the Server NAT tab in the NAT section of Monowall, and I can make Inbound NAT rules to suit incoming traffic. This is working fine to both servers, so that each server can accept incoming mail, http etc. However I have noticed that because of this setup Reverse DNS is not working correctly, the servers IP appears as my DSL IP and I cannot ping the IPs of each server from the outside.

I read that the way for this to work is to setup 1:1 NAT, and after setting this up my servers IPs appeared to be their true IP, and I could now ping their IP from outside. However after setting up an inbound port 25 rule to one server I found I couldnt make another for the other server, which I need to do.

Is there a way that the servers local LAN IP could be the actual public IP, or have I missed a vital step in setting this up somehow? I cant figure out how to have multiple incoming rules for the same port to different IPs.

Thanks!