The following filters are available for manipulating the response:

* cache_control_cachedirective
  The actual Cache-Control header as set by this plugin. An empty value makes
  the request non-cacheable. Any other value must meet the requirements for a
  cache-directive response header as defined in:
  https://tools.ietf.org/html/rfc7234#section-5.2
  https://tools.ietf.org/html/rfc7234#section-5.2.2 

* cache_control_nocacheables
  Boolean determining whether the current request is a cacheable or not. FALSE
  means it’s cacheable, TRUE means it’s not.


By the by, the Cache Control for WordPress project welcomes your patches.