Locale code for Simplified English?

I’m wanting to create a ‘simplified English’ version of a website that could be accessed by those with limited English skills or used as a basis for machine translation. The linguistic criteria for this are rather variable (see for example this Simple English Helper Tool). The main distinctive feature would likely be that, in seeking to make the vocabulary and grammar simpler, the resultant text would be less acceptable to a native English reader.

I would not think there was any great need of a specific translation effort for WordPress itself. The default en_us translations would probably suffice, as we could normally assume that WordPress users of simplified English would either be using their own localeLocale Locale = language version, often a combination of a language code and a region code, for instance es_MX denotes Spanish as it’s used in Mexico. A list of all locales supported by WordPress in https://make.wordpress.org/polyglots/teams/ settings for the back end or else have a reasonable understanding of English computer terminology.

As far as I am aware there is currently no locale code for this purpose: but do folk think it would be worth having or know if something suitable already exists? If none exists, how about something that’s not too likely to be used as a normal locale code, such as en_ww (World Wide)?