create field to set base url

Hi, thanks for this module.
I have a site that has 2 domains pointing to it, only one of those domains is intended for the public. when OG metatags outputs the tags, it does so based on the current url apparently, but i want it to be always the publicly visible domain. A bit like canonical urls, always pointing to the base page.

here is an example:

1) <meta property="og:url" content="http://direct.xxxx.com/rest-of-url" />
2) <meta property="og:url" content="http://xxxx.com/lifestyle/rest-of-url" />

I always want og:url of path #2, and similarly for images too or any other tag that includes the full site address.
Nodewords module which provides the conventional meta tags has this implemented, with a text field where you provide the base url you want (see screenshot).
Could this please be implemented in OG metatags?

Thanks,