Your idea might confuse your classifier even further, the first one
Indeed you can put a custom dimension in duckling, bear in mind it is written in haskell so it is quite a learning curve.
Simplest would be to add a regex extractor in your pipeline you save your patterns linked to an entity in a json file. load the json on parse and do re.match().
python has a very good regex library, you can even generalize this for many different entities and you don’t need to train these entities using a CRF