Making carte blanche changes sensitive/critical constructs to private fields as protected is a poor design practice.
We have met similar situation before. And the good practice is to
a) provide the nature and reason of extension one is looking for. This way some alternatives can be suggested that does not require such changes.
b) It is understood that some work may require some degree of access relaxation. But it is more prudent to make those relaxation as and when they are required