Redirect and switch to default language if no translation exists

We plan to add entity_translation to add some translated content in some fields in a few content types to an existing (currently primarily language-neutral) site. Pages will always have mixed language content, as we have no plans to translate the site's navigation, etc. at present. We want to use language path prefix in the URLs for pages with majority-translated content. On these pages we wish to re-direct users back to the default language page (i.e. with no language prefix in the URL), for those nodes and other links shown on the page (navigational menus, user pages etc.), that have minimal or no translated content on them.

For example, a page such as http://example.com/fr/this-blog-is-about-france which has its body field and others translated to French would have links to other French blogs on it, with their URLs having the /fr prefix. However links to the home page, to non-translated blogs, etc. would not have the prefix, and navigating to one of these pages would switch the selected language back to the default (English).

We’ve looked at using globalredirect, multilink and a number of other modules which seem like they should make this possible, but have yet not found a working solution. Any hints on how to achieve this?