> I don't think it should be called "strict" though, as that would imply that we comply with RFC 4627 strictly
> (which is not true without passing allow_nan=False for dump() or  passing a parse_constant function for load())

What if the strict mode implied both of these things?

FWIW, I’m +1 for a doc section about how to achieve strict mode with special arguments and callbacks (if the recent doc patch does not already have that), and +0 on adding it to the code itself.