Path Hierarchy Tokenizer with doc values

Im splitting a category field using the Path Hierarchy Tokenizer which I want to use for aggregations. Since the field must be text so that the content is analyzed (using the Path Hierarchy Tokenizer), I cannot use doc values. There is huge number of categories so using field data isn't really an option.
Is there any way to transform the output of the path hierarchy tokenizer from text to keyword (For example using a Token Filter) so I can use doc values? If not are there any alternatives, for example writing a plugin to introduce a new HIERARCHY type?