If your site isn’t on a blacklist it should be fine to just host your content in LON1 and have the china-based CDN store your assets.

You need to change your application to reference the resources on the cdn instead of linking to your own server, so your LON1 box will serve the dynamic web content and the CND boxes will serve your images / css / js etc.

You’ll end up having to call something like this from your templates:

  function image_url(name){
     if (user_is_from_china) { return "https://you.thecdn.cn/static" + name } 
    else  { return "https://your.domain/static" + name }
  }

CloudFlare does a man-in-the-middle version of this, and they change your content on the fly - if you’re planning on having support for multiple CDNs you’ll likely need more control over the urls used in your pages.