How to get CME User Preferences language within XPM WebsiteFrame

Question

I have built what I call an Edition Panel for XPM that basically using a C# TBB creates some HTML+JS with XPM markup and enables full component edition.

I want to vary some things of the Edition Panel based on the user preferences language of the CME so I need to know the language of the CME within the website frame while editing from XPM.

I figured out some hacks to get it:

• I could create a dummy SiteEdit extension with some .resx files with a lang key inside and the current language as value. This will be loaded into Tridion.LocalizedStrings that is available on the website when it's been edited with XPM.
• Also I started to think about extending Anguilla's security restrictions at Tridion.Web.UI.SiteEdit.EditorXDMHandler, aka $sexdm, to allow Tridion.Utils.CrossDomainMessaging to send this information back to the website when required, but I'm not sure if this is feasible.

Although I figured out this hacks I want to know if there is a proper way (or best/simple/elegant way) to share this information with the external website or I'm about to commit a horrible sin.

Thank you.