SAP Enterprise Portal 7.40 as a proxy

Hello experts

I would like to know if the SAP Enterprise Portal 7.40 can act as a Proxy for internal SAP servers(WebChannel, MII, ERP, CRM, etc). Currently this is my situation: users access the E.P. via a Web Dispatcher and then the E.P. forwards the user to the same WebDisp that connects them to the ERP, MII, WebChan and CRM:

The problem is that I have to publish all the servers on the internet with a public IP because users access for instance the ERP on a frame of E.P. but this one is only a link to its public IP. I've seen on the log of ERP's WebDisp that the source addresses are public IPs of users on the Internet, not of the E.P.

There is a way to have the E.P. be a Proxy for the other services? Because now my E.P. is like a "Internet favorites" with SSO. So I need a situation like this(OK, I can put a WedDisp in front of E.P.):

(E.P. now is not in the DMZ, is in the LAN)

Thanks in advance,
Marco