My team has needed custom Confluence URLs for quite some time. It wasn't an option for us to wait for this functionality, so we built it ourselves.
We've named our solution Whitelabel and are turning it into a product so that others can customize their Confluence (and Jira) URLs too.
We're in the late stages of development and are collecting beta testers for our launch in a couple weeks. Sign up at the link above if you're interested in taking part.
Note that we don't build a separate website on top of your Confluence pages - you keep your original pages, just with the ability to customize the URLs for your brand!