WordPress Settings with Dynamic DNS and Forwarding and Masking

I have WP 3.3 installed on a home server. I am using Dynamic DNS and DNS Masking/Forwarding so I can use makethevapor.com as the URL rather than my dynamic dns address.

I have found that the only combination of settings that work is if under Settings -> General I sepecify the URL to be my dynamic dns url and then I can access the site perfectly remotely using the dynamic dns address. However if I try changing it to access it from my makethevapor.com I lost all CSS formatting and/or I am unable to login. When you click the login icon it just hangs.

How do I get this DNS forwarding to work correctly?

If I cannot get it working correctly can I assume the only thing that will not work is the ability to login and access admin pages?