> This would actually make it harder to strip docstrings e.g. during unmarshalling, since you don't know which constants refer to docstrings.

We can not strip class docstring anyway.

One idea to strip docstring during startup: Add new opcode only for storing __doc__.
We can use it for both of func and class. The opcode will store None if "remove docstring during startup" option is enabled. And surrounding code objects will be released after executing global/class body.