Add a JSON field type, with an editor (https://github.com/cantino/jsoneditor). Can be used with Bolt's json_decode twig filter to make json values/arrays/subobjects available in Twig templates. Stores the entire JSON as a string in the database. The editor provides a textarea to hand-edit the JSON if desired. NOTE: editor may fail to load if the field is not empty or valid JSON - a bug to be worked out.