Hi Bryan,
your SAP Server internally still has the same IP - therefor you should use the same connection parameters.Only "problem" is what you put in your WSDLs as location.
I see 3 possible setups for your network connection:
1. VPN - no prefernces needed
2. Dynamic public IP - since the external IP can change, it would be good to use a DynDNS service ( hostname is then put in WSDLs )
3. Stable public IP - use this IP in your WSDLs for external access.
regards,
Maik